Editor's Note: Ambassador J. Christopher Stevens and three others were killed at the U.S. Consulate in Benghazi. This story is continuing to develop. Follow along below for our continued coverage of the attacks, reaction and what impact it will have. For coverage in Arabic, please visit CNN Arabic.

[Updated at 5:36 p.m. ET] U.S. Sen. John McCain, R-Arizona, referring to last year's revolt of Libyans against Moammar Gadhafi, said on the Senate floor Wednesday that Libyans "rose up last year to free themselves from exactly the kinds of murderers and terrorists who killed our American citizens yesterday in Benghazi."

"Their enemies are our enemies," McCain said.

[Updated at 4:38 p.m. ET] In 2008, Stevens - who then was the deputy chief of the U.S. mission in Libya - warned in a diplomatic cable about jihadist sentiment growing not far from Benghazi, CNN's Ashley Fantz reports.

[Updated at 4:28 p.m. ET] A statement released on the behalf of the 80 cast and crew members of "Innocence of Muslims," a film that reportedly prompted Tuesday protests at the U.S. Embassy in Cairo and the U.S. Consulate in Benghazi, indicates that they are not happy with the film and were misled by the producer.

"The entire cast and crew are extremely upset and feel taken advantage of by the producer. We are 100% not behind this film and were grossly misled about its intent and purpose," the statement says. "We are shocked by the drastic re-writes of the script and lies that were told to all involved. We are deeply saddened by the tragedies that have occurred."

As this post has previously noted, U.S. officials speaking on condition of anonymity say they believe the attack that killed four Americans in Benghazi was planned before the protests and was not prompted by the film, and that the attackers perhaps used the protest as a diversion. (See 2:48 p.m. update.)

[Updated at 4:16 p.m. ET] A U.S. official has said that there was no clear stream of intelligence that indicated the Benghazi attack was coming, CNN's Suzanne Kelly reports.

[Updated at 3:16 p.m. ET] Pakistan's foreign ministry has issued a statement condemning the film that reportedly sparked Tuesday protests outside the U.S. Embassy in Cairo and perhaps the U.S. Consulate in Benghazi. As this post has previously noted, U.S. officials speaking on condition of anonymity say they believe the attack that killed four Americans in Benghazi was not prompted by the film. (See 2:48 p.m. update.)

Here's the Pakistani statement on the film, which it says maligns "the revered and pious personality of Prophet Muhammad (PBUH)":

"Such abominable actions, synchronized with commemoration of atrocious events like 9/11, provoke hatred, discord and enmity within societies and between peoples of various faiths. The event has deeply hurt the feelings of the people of Pakistan and the Muslims all over the world. Pakistan is a strong proponent of inter-faith harmony and believes that all manifestations of extremist tendencies must be opposed."

[Updated at 3:01 p.m. ET] The Pentagon and other U.S. agencies will review a video of the attack on the U.S. Consulate in Benghazi, according to a senior defense official. The official had not seen the video and provided no details about the source of the video, CNN's Chris Lawrence reported.

[Updated at 2:48 p.m. ET] U.S. sources say they do not believe the attacks that killed Stevens and three other Americans in Benghazi, Libya, were in reaction to the online release of a film mocking Islam, CNN's Elise Labott reports.

"It was not an innocent mob," one senior official said. "The video or 9/11 made a handy excuse and could be fortuitous from their perspective, but this was a clearly planned military-type attack."

This meshes with information recorded earlier in this post, including that U.S. sources told CNN that the Benghazi attack was planned, and that perhaps a protest against the film was used as a diversion. Also, a London think tank with strong ties to Libya speculated Wednesday that Stevens was the victim of a targeted al Qaeda attack "to avenge the death of Abu Yaya al-Libi, al Qaeda's second in command killed a few months ago." (See 12:51 p.m. update.)

The Libya attacks came on the same day that protesters in Cairo, Egypt, scaled the walls of the U.S. Embassy in Cairo. Protesters there reportedly were upset about an online film considered offensive to Islam.

The U.S. sources also say that two U.S. properties were attacked in Benghazi: first, the main compound where Stevens was, and later, and attack on another U.S. compound in Benghazi.

Regarding the attack on the main compound, a U.S. source says three people - Stevens; Sean Smith, a U.S. Foreign Service information management officer; and a security officer - were in a safe room. The house was on fire (CNN has previously reported the building was on fire after a grenade attack), and the security officer got out. The officer then went back in for Stevens and Smith, and he found Smith's body and retrieved it. The officer could not find Stevens, the source said.

CNN previously reported that, according to a senior U.S. official familiar with the details of the attack, four Americans - including Stevens and Smith - died after succumbing to smoke inhalation.

[Updated at 2:21 p.m. ET] The U.S. Embassy in Afghanistan and the NATO-led International Security Assistance Force issued a joint statement Wednesday condemning the killing of four Americans at the U.S. Consulate in Benghazi, Libya.

"As the U.S. Secretary of State Hillary Clinton said, 'Some have sought to justify this vicious behavior as a response to inflammatory material posted on the Internet. The United States deplores any intentional effort to denigrate the religious beliefs of others. Our commitment to religious tolerance goes back to the very beginning of our nation. But let me be clear: There is never any justification for violent acts of this kind.'"

[Updated at 1:41 p.m. ET] Seattle Children’s Hospital released the following statement on behalf of the sister of Ambassador Christopher Stevens, who is a doctor at the hospital.

"Dr. Anne Stevens is deeply saddened by the tragic death of her brother U.S. Ambassador Christopher Stevens," the statement said. "She and her family request that you respect their privacy at this time."

[Updated at 1:19 p.m. ET] The ambassador of Libya to the United States, Ali Aujali, released the following statement regarding the attacks:

"We condemn yesterday's deplorable attack on the U.S. Consulate in Benghazi and those who are responsible for it in the strongest terms. The Government of Libya stands by the U.S. in opposing acts of terrorism. We are committed to bringing the attackers who perpetrated these crimes to justice.

Ambassador Chris Stevens and the other American who were killed served the U.S. Government bravely. Ambassador Stevens worked tirelessly in support of freedom in Libya. When Stevens was appointed as Special Representative of the U.S. to the National Transitional Council of Libya in April 2011, he faced enormous challenges. He served as the principal liaison of the U.S. to the opposition in Libya and he helped coordinate the U.S. response to the enormous humanitarian crises in Libya. He handled these responsibilities with a calm demeanor and strong determination in the midst of a war.

After the liberation of Libya, the new Libyan Government was overjoyed to learn that Stevens had been appointed as the U.S. Ambassador to Libya. He served in that role with great distinction and all Libyans owe him a debt of gratitude for his years of service in support of Libya. The acts that led to the tragic loss of his life and the other Americans who served with him were perpetrated by a small group of criminals and are not supported by the Libyan people. We stand with the U.S. Government in offering our deepest condolences to the family of Ambassador Stevens and the other Americans who were killed and to the entire State Department.

I have had the honor to work side by side with Ambassador Stevens and to call him a friend for many years. I will never forget the zeal and passion that he brought to his work. He was a dedicated diplomat and a true gentleman. The families of Ambassador Chris Stevens, Foreign Service Officer Sean Smith, and the two American security staff who were killed in yesterday's terror attack are in our thoughts and prayers today."

[Updated at 1:19 p.m. ET] The United Nations Security Council released the following statement with regard to the attack:

"The members of the Security Council condemned in the strongest terms the attack on the United States of America’s diplomatic mission and personnel in Benghazi, Libya on 11 September, which resulted in the deaths of four American diplomatic personnel, including the Ambassador, and injuries to diplomatic personnel and civilians. They expressed their deep sympathy and sincere condolences to the victims of this heinous act and to their families.

The members of the Security Council also condemned in the strongest terms the attack on the United States Embassy in Cairo, Egypt on 11 September.

The members of the Security Council underlined the need to bring perpetrators of these acts to justice.

The members of the Security Council reaffirmed that such acts are unjustifiable regardless of their motivations, whenever and by whomsoever committed.

The members of the Security Council recalled the fundamental principle of the inviolability of diplomatic and consular premises, and the obligations on host Governments, including under the 1961 Vienna Convention on Diplomatic Relations and the 1963 Vienna Convention on Consular Relations, to take all appropriate steps to protect diplomatic and consular premises against any intrusion or damage, and to prevent any disturbance of the peace of these missions or impairment of their dignity, and to prevent any attack on diplomatic agents and consular officers.

In this context, and expressing their deep concern at these attacks, the members of the Security Council called on all authorities to protect diplomatic and consular property and personnel, and to respect their international obligations in this regard.

The members of the Security Council underscored the durable commitment of the international community to support Libya’s successful transition to a peaceful and prosperous democracy."

[Updated at 1:16 p.m. ET] Vice President Biden was delivering remarks at Wright State University in Dayton, Ohio and had strong words for those responsible for the attack.

"Let me be clear we are resolved to bring to justice their killers. We will work to do just that,"Biden said. "There is no place in the civilized world for senseless murder like what occurred last night."

[Updated at 1:14 p.m. ET] President Obama has ordered all flags be flown at half-staff at the White House, all public buildings and grounds, military posts in the U.S. and embassies and consular offices abroad until sunset on September 16.

Obama said the declaration was made as a "mark of respect for the memory of John Christopher Stevens, United States Ambassador to Libya, and American personnel killed in the senseless attack on our diplomatic facility in Benghazi."

[Updated at 12:51 p.m. ET] A London think tank with strong ties to Libya speculated Wednesday that Stevens was actually the victim of a targeted al Qaeda revenge attack.

The assault "came to avenge the death of Abu Yaya al-Libi, al Qaeda's second in command killed a few months ago," the think tank Quilliam said Wednesday. It was "the work of roughly 20 militants, prepared for a military assault," the think tank said, noting that rocket-propelled grenade launchers do not normally appear at peaceful protests, and that there were no other protests against the film elsewhere in Libya.

The planned attack came in two waves, one which prompted U.S. officials to leave the consulate for a secure location. The second wave was directed at the place of retreat, Quilliam said, citing unnamed sources on the ground in Benghazi and abroad.

“These are acts committed by uncontrollable jihadist groups. We hope Libya will seize this opportunity to revive its policy of Disarmament, Demobilisation and Re-integration (DDR) in order to facilitate an end to the spread of such attacks, with the help of the International Community," Noman Benotman, President of Quilliam, said in a press release. "We hope that the International Community, including NATO member states and especially the U.S., will continue their excellent work in Libya which began with the overthrow of the dictator Gadhafi after 42 years in power.”

[Updated at 12:23 p.m. ET] A senior U.S. official tells CNN that U.S. unmanned surveillance drones are expected to begin flying over Benghazai and other locations in eastern Libya to look for jihadi encampments and targets that may be tied to the attack on U.S. State Department personnel.

The proposal for use of drones is expected to be approved shortly by the Pentagon and the White House, CNN's Pentagon Correspondent Barbara Starr reported. The official said the plan is for U.S. surveillance drones to gather the intelligence and then hand it off to the Libyans to strike the targets.

In June, Nic Robertson, Paul Cruickshank and Jomana Karadsheh reported that the U.S. was flying surveillance missions with drones over suspected jihadist training camps in eastern Libya because of concerns over rising activity by al Qaeda and like-minded groups in the region, according to a senior Libyan official. But the source said that to the best of his knowledge, they had not been used to fire missiles at militant training camps in the area

[Updated at 12:23 p.m. ET] A grenade attack created a fire in the U.S. consulate building in Benghazi, which created a very complicated and complex situation for those inside, according to a senior U.S. official familiar with the details of what happened.

"Folks inside were fighting the fire inside and the attackers outside. It was a cascading casualty, and Amb. Chris Stevens and the others got separated trying to escape to the roof of the building, ultimately succumbing to smoke inhalation," the U.S. official told CNN's Jill Dougherty. "There will be more details as we go forward, but there were several valiant attempts to re-enter the burning building to find and save the ones we lost. Valiant but unsuccessful."

Another senior official with the State Department confirmed the details as well.

[Updated at 12:11 p.m. ET] Tuesday's attack on the U.S. Consulate in Benghazi, Libya, was planned in advance, and the attackers used the protest outside the consulate as a diversion, U.S. sources told CNN Wednesday.

The sources could not say whether the attackers instigated the protest or merely took advantage of it. The sources do not believe Ambassador Chris Stevens was specifically targeted.

[Updated at 12:01 p.m. ET] After Stevens was named U.S. ambassador to Libya in May, he recorded a three-minute video in which he introduced himself to Libyan citizens and said he was “thrilled” to watch Libyans “stand up and demand their rights” during the 2011 revolt against Moammar Gadhafi.

“Assalamu alaikum. My name is Chris Stevens and I’m the new U.S. ambassador to Libya,” Stevens said in the video produced by the State Departments’ public diplomacy communications bureau. “I had the honor to serve as the U.S. envoy to the Libyan opposition during the revolution, and I was thrilled to watch the Libyan people stand up and demand their rights.

“Now I’m excited to return to Libya to continue the great work we’ve started, building a solid partnership between the United States and Libya to help you, the Libyan people, achieve your goals.”

In the video, which was subtitled in Arabic and recorded in Washington, Stevens told viewers that he didn't know much about the Arab world when he grew up in California. But after graduating from the University of California in Berkeley, he joined the Peace Corps and taught English in Morocco for two years and “quickly grew to love this part of the world.”

“Since joining the foreign service, I’ve spent almost my entire career in the Middle East and North Africa,” Stevens said.

He expressed optimism about the future of U.S.-Libyan relations.

“One of the things that impressed me when I was last in Libya was listening to stories from the people who were old enough to have travelled and studied in the United States back when we had closer relations. Those days are back.”

Watch Stevens in the video or read more about him here.

[Updated at 11:48 a.m. ET] The FBI is expected to be actively involved in investigating the killings of U.S. personnel at the consulate in Benghazi, according to a senior law enforcement official.

“Any time an American is attacked or killed abroad the FBI has the authority to investigate,” said the official who asked not to be identified because he is not authorized to comment.

The FBI is not yet commenting on its role, deferring all questions to the State Department which has been designated the lead agency in the aftermath of the attacks.

The first FBI personnel who normally arrive at the crime scene of an overseas incident are legal affairs attaches from the region. The FBI has “legats” in both Algiers and Cairo, but does not yet have agents stationed in Libya.

They are generally followed by teams of agents with missions to help provide security to protect the crime scene, collect evidence and conduct forensic analysis. A senior law enforcement official said an investigation would have to be conducted before the incident could be declared an act of terrorism.

[Updated at 11:42 a.m. ET]  A statement by Condoleezza Rice has been released by Stanford University:

"I am saddened by the tragic loss of life at our Consulate in Benghazi. Ambassador Chris Stevens was a wonderful officer and a terrific diplomat who was dedicated to the cause of freedom. His service in the Middle East throughout his career was legendary," she said. "My thoughts and prayers are with the loved ones of all of the fallen. They will be sorely missed but never forgotten."

[Updated at 11:23 a.m. ET] The President is meeting with State Department employees today to express his solidarity with our diplomats stationed around the world. He will give thanks for the service and sacrifices that our civilians make, and pay tribute to those who were lost.

[Updated at 11:07 a.m. ET] Martin Indyk, a U.S. assistant secretary of state for the Middle East during President Bill Clinton’s second term, said Stevens was “always enthusiastic and cheery in everything he did, and he always wanted to be on the front line.”

Indyk knew Stevens in part because Stevens was his Iran desk officer. He said that because of Stevens’ enthusiasm, he wasn’t surprised that he accepted the charge to be an envoy to the Libyan opposition during the revolt against then-Libyan leader Moammar Gadhafi.

Indyk said the attack was “clearly not the intention of the Libyan government,” noting it worked with Stevens and was quick to apologize after his death.

“By the same token, this was no mob lynching. It was demonstration with RPGs. There was something more organized behind this attack, I suspect, and it’s important for the (Libyan) government” to determine what happened and deal with the attackers, Indyk said.

[Updated at 10:54 a.m. ET] Leaders of Afghanistan are concerned there could be violence after Friday prayers over the anti-Islam film that has angered many in the Arab world, including in Libya and Egypt, a deputy spokesman for President Hamid Karzai said Wednesday.

"There could be many deaths," the spokesman said.

The Afghan Cabinet met to discuss the concerns Wednesday morning.

[Updated at 10:43 a.m. ET] President Barack Obama said the United States condemns in the strongest terms the "outrageous" attack that took place in Benghazi, Libya.

"Today, the American people stand united in holding the families (of those killed) in our thoughts and in our prayers."

Obama said he will work with the Libyan government to bring to justice the attackers.

“We will not waver in our commitment to see that justice is done for this terrible act - and make no mistake, justice will be done," he said.

Obama said he rejects all efforts to denigrate the religious beliefs of others, but there is no justification for this attack, adding that the he world must stand together to reject these brutal attacks.

"No attacks of terror will ever shake the resolve of (the United States)," Obama said.

He also said, like Secretary of State Hillary Clinton, that it is important to make sure this attack does not change the work being done in Libya.

"This attack will not break the bonds between the U.S. and Libya," he said.

[Updated at 10:37 a.m. ET] House Speaker John Boehner ordered flags to be flown half-staff at the U.S. Capitol in honor of those who died in Benghazi, Libya. He will also lead the House in a moment of silence.

[Updated at 10:35 a.m. ET] Mitt Romney on Wednesday called the killing of the U.S. ambassador to Libya and three other embassy personnel "outrageous" and "disgusting," and said "America will not tolerate attacks against our citizens and against our embassies."

[Updated at 10:31 a.m. ET] Former U.S. secretary of state Condoleezza Rice told CNN's Zain Verjee the attack was a "terrible tragedy."

"He was a wonderful officer and a terrific person," she said. "He was a patriot with an unshakeable belief in the power of freedom."

[Updated at 10:29 a.m. ET]About 50 U.S. Marines from a rapid-reaction force are heading for Libya in the wake of an attack on the U.S. consulate in Benghazi that killed the ambassador and three other Americans, U.S. officials said Wednesday, CNN Penatgon Correspondent Barbara Starr reported.

[Updated at 10:07 a.m. ET] U.S. Ambassador Chris Stevens, who was killed in Libya overnight, "risked his life to stop a dictator" when he was sent to Benghazi last year as the American envoy to the rebels working to topple Moammar Gadhafi, Secretary of State Hillary Clinton said Wednesday in the wake of an attack on the U.S. Consulate in Benghazi that left Stevens and three other Americans dead.

"This is an attack that should shock the conscience of people of all faiths around the world," Clinton said. "We condemn in the strongest terms this senseless act of violence and we send our prayers to the families friends and colleagues of those we’ve lost."

Clinton said that the four people who died represent the diplomats all over the world who risk their lives because "they believe the United States must be a force for peace and progress in the world."

"These aspirations are worth sacrificing and striving for," Clinton said.

Clinton said that she understand the attack in Libya was hard for most to fathom given the recent efforts by NATO in the area.

"Today many Americans are asking, indeed I asked myself, how could this happen? How could this happen in a country we helped liberate, in a city we helped save from destruction?" Clinton said.

This question shows how complex the world can be, she said, adding that the attack was orchestrated by a small and savage group, and not the larger people and government of the country that Americans still fight to defend.

During the attack armed militants assaulted the compound and set fire to the building, Clinton said. She added that Libyans and Americans battled the attackers together.

"When the attack came yesterday Libyans stood and fought to defend our post. Some were wounded," Clinton said. "Libyans carried Chris’  body to the hospital and helped rescue and lead other Americans to safety."

Clinton said she wanted to ensure that the relationship between the U.S. and Libya to become a casualty of the attack.

"A free and stable Libya is still in America’s interest," she said. "We will not turn out backs on that."

Clinton also addressed the angry crowd that marched on the consulate on Tuesday, furious about an online film considered offensive to Islam, Libya's Deputy Interior Minister Wanis al-Sharif said Wednesday. The U.S. mission in Egypt was also attacked Tuesday in response to the film. She maintained that the U.S. has a commitment to religious tolerance, but it only goes so far.

"Let me be clear, there is no justification for this. None," she said. "Violence like this is no way to honor religion or faith. And as long as there are those that would take innocent life in the name of God, the world will never know a true and lasting peace."

Clinton added that because the attacks happened on the anniversary of September 11, it had extra meaning for Americans.

"We are reminded that our work is not yet finished," she said.

The United States "will not rest until those responsible for these attacks are found and brought to justice," Clinton said.

[Updated at 9:50 a.m. ET] Senate Majority Leader Harry Reid praised diplomatic corps members on Wednesday morning saying that the four "Americans that lost their lives yesterday exemplify the courage and sacrifice that happens everyday in diplomatic posts around the globe."

Reid said that Stevens, the ambassador, was a Peace Corps volunteer in Morocco, where he taught English. Stevens served in the foreign service in Jerusalem, in Cairo, Saudi Arabia, Iran and staff assistant in the Bureau of Near Eastern Affairs, Reid said.

“He had an education that was really unbelievably strong and powerful,” Reid said, noting he graduated from Berkeley, got a law degree from Hastings and a Masters from the National War College.

“What a loss to our country,” he said.

Senate Minority Leader Mitch McConnell joined other politicians in condemning the attack.

"I support employing every available tool at our disposal to ensure th4e safety of Americans overseas and to hunt down those responsible for those attacks.    Yesterday we commemorated the anniversary of the attacks of September 11^th and today we are reminded that brave Americans serve us everyday at the risk of their own lives."

[Updated at 9:27 a.m. ET] President Obama will deliver a statement in the Rose Garden at 10:30 a.m. Secretary of State Clinton will also attend, according to a release from The White House. Clinton will also be speaking at the State Department on Wednesday morning.

[Updated at 9:15 a.m. ET] Republican presidential nominee Mitt Romney on Tuesday issued a paper statement sharply critical of President Barack Obama over his handling of violence in the Middle East earlier in the day.

“I'm outraged by the attacks on American diplomatic missions in Libya and Egypt and by the death of an American consulate worker in Benghazi," Romney said in the statement. "It's disgraceful that the Obama Administration's first response was not to condemn attacks on our diplomatic missions, but to sympathize with those who waged the attacks.”

The statement was released by the Romney campaign as the candidate arrived at the Jacksonville, Florida hotel where he was expected to spend the night.

Early Wednesday, Obama campaign spokesman Ben LaBolt issued a statement in response to Romney's statement.

“We are shocked that, at a time when the United States of America is confronting the tragic death of one of our diplomatic officers in Libya, Governor Romney would choose to launch a political attack,” LaBolt wrote.

[Updated at 9:01 a.m. ET] House Speaker John Boehner released the following statement condemning the attack:

“We mourn for the families of our countrymen in Benghazi, and condemn this horrific attack. Eleven years after September 11, this is a jolting reminder that freedom remains under siege by forces around the globe who relish violence over free expression, and terror over democracy - and that America and free people everywhere must remain vigilant in defense of our liberties.”

[Updated at 8:53 a.m. ET] Libya's government apologized to the United States and to the family of Ambassador Chris Stevens, who was killed an attack on the consulate in Benghazi.

President Obama was notified Tuesday night that Stevens was unaccounted for and then notified of his death this morning, according to a senior administration official.

[Updated at 8:41 a.m. ET] U.S. Marines are on their way to Libya, to provide additional security to the area, CNN Pentagon Correspondent Barbara Starr reported.

The United States moved to increase embassy security around the world after the attack.

"I have directed my Administration to provide all necessary resources to support the security of our personnel in Libya, and to increase security at our diplomatic posts around the globe," President Barack Obama said Wednesday morning in response to the attack.

[Updated at 8:22 a.m. ET] The U.S. compound in Benghazi, which is now empty, is being looted, according to a Greek contractor for the U.S. Mission in Benghazi.

[Updated at 8:10 a.m. ET] The villa of the UK compound in Benghazi is now being locked down for security reasons, according to a Greek contractor for the U.S. Mission.

The UK consulate has been empty since June, when the British ambassadors' convoy was attacked in Benghazi, according to the Foreign Office in London.

[Updated at 8:03 a.m. ET] A second American killed in Libya on Tuesday was identified on Wednesday. Secretary of State Hillary Clinton named him as Foreign Service Information Management Officer Sean Smith, a ten-year veteran of the State Department, a husband and a father of two. Ambassador Chris Stevens was also killed in an attack on the consulate in Benghazi. The two other victims have not been named.

Clinton's statement is in full below:

"It is with profound sadness that I share the news of the death of four American personnel in Benghazi, Libya yesterday. Among them were United States Ambassador to Libya Chris Stevens and Foreign Service Information Management Officer, Sean Smith. We are still making next of kin notifications for the other two individuals. Our hearts go out to all their families and colleagues.

A 21 year veteran of the Foreign Service, Ambassador Stevens died last night from injuries he sustained in the attack on our office in Benghazi.

I had the privilege of swearing in Chris for his post in Libya only a few months ago. He spoke eloquently about his passion for service, for diplomacy and for the Libyan people. This assignment was only the latest in his more than two decades of dedication to advancing closer ties with the people of the Middle East and North Africa which began as a Peace Corps Volunteer in Morocco. As the conflict in Libya unfolded, Chris was one of the first Americans on the ground in Benghazi. He risked his own life to lend the Libyan people a helping hand to build the foundation for a new, free nation. He spent every day since helping to finish the work that he started. Chris was committed to advancing America’s values and interests, even when that meant putting himself in danger.

Sean Smith was a husband and a father of two, who joined the Department ten years ago. Like Chris, Sean was one of our best. Prior to arriving in Benghazi, he served in Baghdad, Pretoria, Montreal, and most recently The Hague.

All the Americans we lost in yesterday’s attacks made the ultimate sacrifice. We condemn this vicious and violent attack that took their lives, which they had committed to helping the Libyan people reach for a better future.

America’s diplomats and development experts stand on the front lines every day for our country. We are honored by the service of each and every one of them."

[Updated at 7:23 a.m. ET] President Barack Obama confirmed that United States Ambassador Chris Stevens was killed in an attack in Libya overnight, saying he "strongly condemns the outrageous attack."

His statement is in full below:

"I strongly condemn the outrageous attack on our diplomatic facility in Benghazi, which took the lives of four Americans, including Ambassador Chris Stevens. Right now, the American people have the families of those we lost in our thoughts and prayers. They exemplified America's commitment to freedom, justice, and partnership with nations and people around the globe, and stand in stark contrast to those who callously took their lives.

I have directed my Administration to provide all necessary resources to support the security of our personnel in Libya, and to increase security at our diplomatic posts around the globe. While the United States rejects efforts to denigrate the religious beliefs of others, we must all unequivocally oppose the kind of senseless violence that took the lives of these public servants.

On a personal note, Chris was a courageous and exemplary representative of the United States. Throughout the Libyan revolution, he selflessly served our country and the Libyan people at our mission in Benghazi. As Ambassador in Tripoli, he has supported Libya's transition to democracy. His legacy will endure wherever human beings reach for liberty and justice. I am profoundly grateful for his service to my Administration, and deeply saddened by this loss.

The brave Americans we lost represent the extraordinary service and sacrifices that our civilians make every day around the globe. As we stand united with their families, let us now redouble our own efforts to carry their work forward."

[Posted at 6:35 a.m. ET] The United States ambassador to Libya, J. Christopher Stevens, was killed in a rocket attack on the American Consulate in the city of Benghazi on Tuesday, a contractor working at the mission said Wednesday after seeing Stevens' body.

Three American security staff were also killed, said the contractor, who asked not to be named for security reasons.

He said he saw all four bodies on the street Wednesday morning. The bodies are now in the Central Hospital in Benghazi, he said.

Libyan Deputy Prime Minister Mustafa Abushagur appeared to confirm that the envoy had been killed, saying that Stevens was "a friend of Libya, and we are shocked at the attacks on the U.S. consulate in Benghazi."

"I condemn these barbaric acts in the strongest possible terms. This is an attack on America, Libya and free people everywhere," Abushagur said on Twitter.

The contractor in Benghazi said he could hear rocket-propelled grenade attacks last night.

Libyans were also killed, the contractor said, saying the victims were shot on the spot.

The deaths came as protesters attacked U.S. diplomatic compounds in Libya and Egypt on Tuesday, angry about an online film considered offensive to Islam.

The United States has not confirmed the deaths.

Stevens was the American envoy to the Libyan rebel movement that overthrew dictator Moammar Gadhafi last year, based in the rebel capital of Benghazi.

A speaker of Arabic and French, he was among the first American diplomats sent to Libya in 2007 when the United States resumed ties with the Gadhafi regime.

The last time an American ambassador was killed by terrorists was in 1979, when the envoy to Afghanistan, Adolph Dubs, was kidnapped and killed during an attempt to rescue him, according to State Department records.

- CNN's Stephanie Halasz, Jomana Karadsheh, Elise Labott and Kirsten Dewar contributed to this report.