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Six people were killed and 14 others wounded, including U.S. Rep. Gabrielle Giffords, when a gunman opened fire in front of a Safeway supermarket in Tucson, Arizona, authorities said. The congresswoman had been hosting a meeting with constituents Saturday morning when the attack began.

Here are the latest developments as confirmed by CNN:

[Updated at 8:19 p.m.] President Barack Obama will travel to Tucson on Wednesday, and likely will attend a memorial service and visit with the relatives of the shooting victims, many of whom he already has spoken to by phone, two senior administration officials tell CNN.

[Updated at 4:33 p.m.] Suspect Jared Lee Loughner has made a 15-minute initial appearance in a federal court in Phoenix. A judge asked Loughner whether he understood the charges - attempted assassination of a member of Congress; two counts of murder for the deaths of Judge John Roll and Gabriel Zimmerman; and two counts of attempted murder. Loughner replied that he understood.

A preliminary hearing is scheduled for January 24.

[Updated at 2:23 p.m.] Rep. Gabrielle Giffords, D-Arizona, sent an email the night before she was shot at an event in Tucson calling for a more civil tone in politics.

Giffords offered congratulations to Kentucky Secretary of State Trey Grayson, a Republican, after he was named Director of Harvard University's Institute of Politics on Friday.

"After you get settled, I would love to talk about what we can do to promote centrism and moderation," Giffords wrote in the email, provided to CNN by Grayson. "I am one of only 12 Dems left in a GOP district (the only woman) and think that we need to figure out how to tone our rhetoric and partisanship down."

[Updated at 12:43 p.m.] Former Cuban leader Fidel Castro weighed in on the Arizona mass shooting that killed six and injured 14, including Rep. Gabrielle Giffords, in a column distributed Monday.

[Updated at 12:15 p.m.] Arizona Rep. Gabrielle Giffords remains in critical condition but her condition has stabilized, doctors at Tucson's University Medical Center indicated Monday.

"We're not out of the woods yet" but are optimistic about her prospects of recovery, said Dr. Michael Lemole, chief of neurosurgery.

[Updated at 12:03 p.m.] Two patients from Saturday's shooting have been discharged and only two remain in intensive care, the chief of the department of surgery at Tucson's University Medical Center announced Monday.

Eight patients remain at Tucson's University Medical Center, Chief of Emergency Medicine Peter Rhee announced Monday. Five are in serious condition, two are in good condition, and one is in critical condition, Rhee said.

[Updated at 11:01 a.m.] President Barack Obama led the nation in a moment of silence Monday for victims of the weekend massacre in Tucson, Arizona.

[Updated at 9:47 a.m.] Judge John Roll,  one of the victims in the Arizona shooting, will leave behind a legacy as a man who put excellent attention into every component of his life, his former clerk spoke told CNN's T.J. Holmes.

[Updated at 9:15 a.m.] Dr. Steven Rayle, helped hold the Arizona gunman down and Patricia Maisch, grabbed the magazine cartridge after suspect Jared Lee Loughner allegedly opened fire in a Safeway in Tuscon, Arizona.

"You just react," Maisch told CNN about approaching the gunman. "You just do it."

[Updated at 9:01 a.m.] The University Medical Center in Tucson is expected to give an updated diagnosis on Congresswoman Gabrielle Giffords condition later Monday morning after she was shot in the head.

Chief of neurosurgery at the hospital, Dr. Michael Lemole, told CNN that Rep. Giffords is 'holding her own' and that no change in her condition is a good thing.

[Updated at 8:49 a.m.] Ben McGahee, Jared Lee Loughner's former teacher at Pima Community College told CNN he believed suspect Jared Lee Loughner was a troubled man and that he was "scared of what he could do.'

[Updated at 8:34 a.m.] While the motivation for Saturday's attack in Tucson, Arizona are still unclear, a concern in Washington and in the nation at large is whether or not the current political rhetoric has gotten out of control.

Rep. Debbie Wasserman Schultz warns that while "we cannot allow incidences like this intimidate" we still must remember that "words matter."

[Updated at 8:00 a.m.] Pima County Sheriff Clarence Dupnik, whose department is working on the case, said they have evidence showing Jared Lee Loughner "specifically targeted the congresswoman."

[Updated at 7:40 a.m.] Arizona State Representative Steve Farley talked to CNN about Gabrielle Giffords and her family who he described as remaining 'strong' and 'optimistic.'

[Updated 4:50 a.m.] Astronaut Mark Kelly, Giffords' husband, released his first public statement since the weekend shooting rampage outside an Arizona supermarket that left his wife critically injured. He thanked supporters, expressed
condolences to families of other victims and suggested that well-wishers make donations to Tucson's Community Food Bank and the American Red Cross. "Many of you have offered help. There is little that we can do but pray for those who are struggling," he said.

[Updated Monday at 2:12 a.m.] Suspect Jared Lee Loughner is scheduled to make an initial appearance before a federal magistrate in Phoenix, Arizona, Monday at 2 p.m. (4 p.m. ET),  prosecutors said.

[Updated 9:45 p.m.] Suspect Jared Lee Loughner tried to buy ammunition at a Wal-Mart a few weeks back but was turned down because of his behavior, a law enforcement source said. He then successfully bought it at a different Wal-Mart, according to the source.

[Updated 9:16 p.m.] A woman credited with wrestling an ammunition magazine from the suspect says she didn't have time to think about what she was doing. "(The suspect) pulled the magazine out of his pants pocket and it dropped onto the sidewalk. And before he could reach it, I got it," Patricia Maisch said.

[Updated 7:49 p.m.] Suspect Jared Lee Loughner was rejected by the Army for military service after failing a drug test in 2008, according to an administration official.

[Updated 7:43 p.m.] The U.S. Supreme Court says it will observe the moment of silence that President Barack Obama called for at 11 a.m. ET Monday. To accommodate this, the court will convene 10 minutes early, at 9:50 a.m. ET, so that the day's first argument before the court will be completed by 11 a.m.

[Updated 7:36 p.m.] House Democrats and Republicans participated in a rare bipartisan conference call Sunday to discuss the condition of Rep. Gabrielle Giffords as well as security concerns for members of Congress.

[Updated 6:33 p.m.] According to a federal agent's affidavit, U.S. District Judge John Roll, who was killed in the shooting, came to the Tucson from Phoenix to discuss the volume of federal cases in Arizona with Giffords.

[Updated 6:28 p.m.] The FBI has confirmed that investigators have found, questioned and cleared a man they had sought as a "person of interest" after the killings. The man was cab driver who dropped suspect Jared Lee Loughner off at the Safeway where Giffords' "Congress on Your Corner" event was being held, a law enforcement official previously said.

[Updated 6:24 p.m.] Veteran federal public defender Judy Clarke, who has experience in several high-profile cases including those of "Unabomber" Ted Kaczynski and convicted terrorist Zacarias Moussaoui, was appointed to defend suspect Jared Lee Loughner, a federal judicial source said.

[Updated 6:01 p.m.] Calls to 911 following Saturday's shooting - released Sunday by the Pima County Sheriff's Office - paint a patchy picture of the scene.

[Updated 4:56 p.m.] Investigators found papers bearing the words "my assassination" and "Giffords" in a safe in the home of shooting suspect Jared Lee Loughner, according to a complaint filed against him in federal court.

[Updated 3:56 p.m.] U.S. Rep. Gabrielle Giffords is the only person wounded in Saturday's shooting who is still in critical condition, doctors at University Medical Center in Tucson said. Three are in serious condition, six are in fair condition, and one has been released, they said.

- Officers of the Arizona Anti-Defamation League issued a statement condemning the attack: "During her years in the statehouse, Rep. Giffords served on the ADL Arizona Regional Board. Her affiliation with ADL, which monitors and exposes hate and extremist groups, contributed to her awareness of the nexus between hate ideology and violence. It is a testament to her dedication to her constituents that despite past threats against her, Rep. Giffords has always been so accessible to the people she represents.  Our thoughts and prayers are with Congresswoman Giffords and the other victims and their families."

[Updated 3:33 p.m.] Investigators have identified and ruled out the "person of interest" they were seeking in connection with the shooting, a law enforcement official said Sunday.

[Updated 3:30 p.m.] Federal authorities have charged Jared Lee Loughner, the 22-year-old suspect in Saturday's Arizona massacre, with first-degree murder, attempted murder and attempting to kill a member of Congress, according to court documents. Read the charges here.

[Updated at 3:25 p.m.] President Barack Obama called for a moment of silence to be held at 11 a.m. ET Monday and ordered flags to be flown at half-staff.

"I call on Americans to observe a moment of silence to honor the innocent victims of the senseless tragedy in Tucson, Arizona, including those still fighting for their lives," the president said in a news release. "It will be a time for us to come together as a nation in prayer or reflection, keeping the victims and their families closely at heart."

[Updated at 2:21 p.m. ET] Law enforcement investigators were speaking with a second person in the Arizona  Safeway shootings case, a law enforcement official told CNN. It is not clear whether this individual is the same person police had sought via the release of a surveillance image from overnight. It is also unknown at this time what connection this individual may have to the investigation.

[Updated at 1:38 p.m. ET] A dark-haired man seen in a picture distributed by authorities apparently "may not have been involved at all, but we still need to verify that," Pima County Sheriff Clarence Dupnik said Sunday.

[Updated at 1:18 p.m. ET] Precautions are in place to ensure the security of public officials after the shooting of an Arizona congresswoman, although authorities are aware of no specific threat against them, FBI Director Robert Mueller told reporters Sunday.

[Updated at 1:12 p.m. ET] The suspect in the Saturday shootings of 20 people at a Tucson, Arizona, grocery store is in federal custody, FBI Director Robert Mueller told reporters. Formal charges are expected against Jared Lee Loughner Sunday afternoon, he said.

[Updated at 12:13 p.m. ET] U.S. Rep. Gabrielle Giffords of Arizona is "able to communicate" with people, and the gunshot wound she sustained Saturday did not cross from one hemisphere of the brain to the other, doctors at Tucson's University Medical Center said Sunday.

[Updated at 12:00 p.m. ET] President Obama spoke by phone late Saturday to Mark Kelly, the husband of Rep. Gabrielle Giffords, who was critically injured in a mass shooting, a senior White House official said. The official told CNN that Obama "expressed his deep concern and full support" for the family in the wake of the tragedy.

[Updated at 8:49 a.m. ET] House Speaker John Boehner has asked that flags on the House side of the Capitol be flown at half-staff in the wake of the shooting in Arizona, marking the death of Gabe Zimmerman, who was Rep. Gabrielle Giffords' director of community outreach.  "An attack on one who serves is an attack on all who serve," Boehner said Sunday.  "Such acts of violence have no place in our society. These tragic events remind us that all of us, in our roles in service to our fellow citizens, comes with a risk. This inhuman act should not and will not deter us from our calling to represent our constituents and to fulfill our oaths of office. No act, no matter how heinous, must be allowed to stop us from our duty," Boehner said.

- Authorities executed search warrants late Saturday night on a car and a residence where suspect Jared Lee Loughner  lived with his parents, a law enforcement source said.

- The law enforcement source said that Loughner's parents appeared to be cooperating with authorities, but the source did not know to what extent.

- Loughner, however, was still not cooperating. He had earlier invoked his right against self-incrimination.

- The sheriff's office said early Sunday that the correct name of one of the victims who died in the shooting is Dorothy Morris.

- The Pima County Sheriff's Department is expected to hold another news conference at 11 a.m. Sunday (1 p.m. ET).

- The University Medical Center in Tucson will offer a patient condition update at 10 a.m. Sunday (12 p.m. ET).

- As of 3:45 a.m. Sunday, Giffords remained in critical condition, said Darci Slaten, spokeswoman for the medical center. Of the nine other shooting victims taken to that hospital, four others were in critical condition and five were in serious condition.

- Early Sunday morning, the sheriff's office released a surveillance camera photo of a male between 40 and 50 years old who is "possibly associated with the suspect." The dark-haired man was last seen wearing blue jeans and a dark blue jacket, and was seen at the location where the shooting occurred.

- At 2 p.m. Sunday, a caucus conference call has been scheduled for House Democrats and their spouses to get an update on the shooting, two congressional sources said.

- At 8:30 a.m., Speaker of the House John Boehner will address the media in West Chester, Ohio, about the shooting.

THE INCIDENT

- Congresswoman Giffords was taking part in a meet-and-greet with constituents called "Congress on Your Corner" outside a Safeway grocery store in Tucson.

- Before the event, she tweeted: "My 1st Congress on Your Corner starts now. Please stop by to let me know what is on your mind or tweet me later."

- The attack happened about 10 minutes into the event.

- Giffords did not have any security with her, said staffer Mark Kimble. "She wants to be as accessible to the people who elected her as possible," he said.

- Dr. Steven Rayle was about 10 feet away from Giffords when the gunman shot the congresswoman. "He continued to fire, sort of rapidly, really at point-blank range," he said, adding that the man was shooting indiscriminately.

- The suspect was tackled to the ground by two men while he was trying to reload, another witness said.

- The gun, which another bystander had wrestled from the gunman, was empty and cocked open. Federal and state law enforcement sources described it as a 9mm Glock outfitted with an extended magazine.

- The shooter had another magazine at the ready, according to Joe Zamudio, who said he was one of the bystanders who pinned the gunman to the ground until police showed up.

- Hearing the shooting, Daniel Hernandez, a trained nurse and a Giffords intern, rushed to see what happened and used his medical training to "apply pressure to the wound and keep her active and alert," said Arizona state Rep. Steve Farley. Hernandez was Farley's former campaign manager.

THE INVESTIGATION

- Officials have not stated a motive for the shooting. The suspect was not talking and had invoked his right against self-incrimination, said Pima County Sheriff Clarence Dupnik.

- At the direction of President Barack Obama, FBI Director Robert Mueller was headed to Arizona to help coordinate the investigation. The FBI is working jointly with local law enforcement. The U.S. Attorney's Office for the District of Arizona said it has about a dozen people working on the investigation.

- The suspect was in federal custody early Sunday morning, said Jason Ogan, spokesman for the Pima County Sheriff's Department. As such, the suspect will not face a first appearance in court Sunday, Ogan said.

- Authorities released a photo of a male between 40 and 50 years old who is "possibly associated with the suspect." The dark-haired man was last seen wearing blue jeans and a dark blue jacket, and was seen at the location where the shooting occurred.

- Authorities did not know whether the person they sought actually had any connection with Jared Lee Loughner, a law enforcement source told CNN. Authorities have a piece of evidence that indicates this second individual was in close proximity to the store, the source said, but declined to elaborate.

- That source also said authorities were seeking search warrants for a residence and for a vehicle in connection with the suspect in custody.

- A law enforcement source familiar with the investigation said the Glock used in the shootings was purchased legally, but did not have the details when or where it was bought. The extended magazine used in the shooting was likely purchased separately and at a different time, the source said. The official said such a magazine does not automatically come with a weapons purchase and it would be extremely rare for them to be sold together in one purchase.

THE CONGRESSWOMAN

- Rep. Gabrielle Giffords, 40, was shot in the head and underwent surgery Saturday. Doctors were optimistic of her chances of surviving. "I'm about as optimistic as it can get in this situation," Dr. Peter Rhee of the University Medical Center said Saturday afternoon. He said the next 24 hours will be key for determining the extent of her recovery.

- First elected in 2006, Giffords is serving her third term in Congress.

- She narrowly beat Tea Party-backed Republican Jesse Kelly in the November midterm elections, garnering 49% to the latter's 47% of the votes.

- Known as a "Blue Dog," or moderate, Democrat, Giffords was a key swing vote in last year's health care reform debate. She didn't make up her mind to vote for the legislation until the final days before the ultimate passing vote.

- She is married to NASA astronaut Mark Kelly, a Navy captain who is scheduled to fly the April space shuttle mission to the international space station. She is the only U.S. representative with an active duty military spouse, according to her website.

- She has no children but is stepmother to Kelly's two children, said Sylvia Lee, president of Pima County Community College in Tucson.

- She had received threats in the past, Lee said. A glass panel at her Tucson office was shattered the day after the health care reform vote last year. Staffers suspected someone shot a pellet gun at the glass. At a town hall meeting, a gun fell out of a constituent's pocket. But Giffords' press secretary, C.J. Karamargin, said he was unaware of any recent threats against Giffords.

- She generally voted with her party, but voted against the auto bailout bill and was one of 19 Democrats to vote against former House Speaker Nancy Pelosi's bid to become the Democrats' minority leader after the midterm elections returned Republicans to power in the House.

- She holds a master's degree in regional planning from Cornell University and a B.A. from Scripps College, where she was awarded a William Fulbright Scholarship to study for a year in Chihuahua, Mexico.

- Before embarking on a political career, she worked for Price Waterhouse Coopers and served as chief executive officer and president of El Campo Tire, her family's business.

- She then served in the Arizona Legislature from 2000 to 2005, where she was the youngest woman elected to the Arizona state Senate.

THE SUSPECTED GUNMAN

- The suspect in the shooting is Jared Lee Loughner, a 22-year-old former community college student, according to an Arizona law enforcement source and a U.S. law enforcement source.

- He railed against government "mind control" and illiteracy in online missives and had "kind of a troubled past," said Pima County Sheriff Clarence Dupnik.

- He also had brushes with the law, the sheriff said without elaborating. "We understand that there have been law enforcement contacts with the individual where he made threats." Court records indicate he had been arrested for possession of drug paraphernalia in 2007, but the charge was dismissed.

- Loughner dropped out of high school in 2006, after his junior year, said Tamara Crawley, a spokeswoman for the Marana United School District in suburban Tucson.

- In 2008, he tried to enlist in the U.S. Army. The Army rejected him, and privacy laws keep the military from disclosing the reason, the service said in a statement to CNN.

- He enrolled at Aztec Middle College, a partnership between Tucson schools and Pima Community College that helps high school dropouts transition to community colleges, the community college President Sylvia Lee told CNN.

- He took classes at the college from 2005 until October 2010, but withdrew after five contacts with police "for classroom and library disruptions" at two campuses between February and September, the school said.

- Loughner was suspended after authorities found a YouTube video in which he called the school "illegal according to the U.S. Constitution, and makes other claims," a college statement said. He quit during an October 4 meeting with his parents and school administrators, and a follow-up letter warned that to return, he had to present a doctor's note stating that "his presence at the College does not present a danger to himself or others."

- On his YouTube page, a list of his favorite books included both Adolf Hitler's "Mein Kampf" and Karl Marx and Friedrich Engels' "The Communist Manifesto," along with works by George Orwell, Ray Bradbury, Ken Kesey, Herman Hesse, Ernest Hemingway, Plato and Aesop's fables.

- "Good-bye friends," read a Saturday morning posting on Loughner's MySpace page, just hours before the shooting. "Dear friends ... Please don't be mad at me. The literacy rate is below 5%. I haven't talked to one person who is literate."

- A December 30 posting read, "Dear Reader ... I'm searching. Today! With every concern, my shot is now ready for aim. The hunt, a mighty thought of mine."

- Online, Loughner complained about the "second Constitution," a term legal scholars sometimes use to describe the post-Civil War amendments that ended slavery, extended the right to vote and required equal protection under the law. Its meaning to Loughner could not be clearly discerned.

- In an apparent reference to Giffords' congressional district, he wrote in a December 15 video message on YouTube: "The majority of people, who reside in District-8 are illiterate - hilarious."

- In the same message he wrote: "If I define terrorist then a terrorist is a person who employs terror or terrorism, especially as a political weapon. I define terrorist."

THE OTHER VICTIMS

In addition to the 12 people wounded in the shooting, the following six were killed:

- John Roll, 63. A native of Pennsylvania, Roll was a federal judge for the U.S. District Court for the District of Arizona who had served the legal system for nearly 40 years. He began his career as a bailiff in Pima County Superior Court and rose to be chief judge for the District of Arizona, a position he held since 2006.

He received death threats two years ago after he ruled that a $32 million civil-rights lawsuit filed by illegal immigrants against a rancher in the state could proceed. He had been assigned to hear the ethnic studies ban case out of Tucson that involves a new law banning certain ethnic studies programs in public schools, according to the lead attorney on the case, Richard Martinez. Chief Justice of the United States John Roberts called Roll's death a tragic loss.

- Christina Taylor Greene, 9. She was born on September 11, 2001, according to CNN affiliate KVOA. Family members described her as "excited" about the political process, and said the desire to learn more about it had motivated her to go to the Gifford event, the affiliate said. Christina had just been elected to the student council at her school, the Arizona Republic reported. She died at a hospital, and not at the scene like the other five.

- Gabe Zimmerman, 30. A Tucson native who was engaged to be married, Zimmerman was the director of community outreach for the congresswoman.

- Dorwin Stoddard, 76. Dory, as his family calls him, was a retired construction worker, said Pastor Mike Nowak at Mount Avenue Church of Christ in Tucson. Witnesses told CNN that Stoddard tried to shield his wife, Mavy, was shot in the head and fell on her. The wife was shot three times in her legs; the bullets were removed and she is expected to make a full recovery.

- Dorothy Morris, 76

- Phyllis Scheck, 79

THE REACTION

- Following the shootings, all legislation on the House schedule for the coming week was postponed, House Majority Leader Eric Cantor said. The decision was made by leaders of both parties and means the House will not vote next week on the repeal of health care reform.

- Although U.S. Capitol Police said there was no evidence of a broader threat involving federal officials, it has advised other members of Congress to take "reasonable and prudent precautions regarding their personal safety and security." The House sergeant at arms also said "it is essential" that lawmakers contact local police to register their home and office addresses.

- Tucson Police Chief Roberto Villasenor said his department had secured the homes and offices of some unnamed federal officials as a "precautionary measure."

- Rep. Chellie Pingree, D-Maine, said an incident like this could have a chilling effect on the frequent weekend listening sessions that many members of Congress have with their constituents.

- In Tucson, supporters gathered outside the University Medical Center, keeping vigil as family members waited with wounded loved ones inside. On the other side of the country, dozens of marchers braved subfreezing temperatures and gusty winds to gather on Capitol Hill for a candlelight vigil Saturday night.

QUOTES

- President Barack Obama: "We do not yet have all the answers. What we do know is that such a senseless and terrible act of violence has no place in a free society."

- Arizona Gov. Jan Brewer: "I am just heartbroken. Gabby is more than just a colleague, she is my friend. She has always been a noble public servant."

- John Roberts, chief justice of the U.S. Supreme Court, on the death of one of the victims, Judge U.S. District Judge John Roll: "Chief Judge Roll's death is a somber reminder of the importance of the rule of law and the sacrifices of those who work to secure it."

- U.S. House Minority Leader Nancy Pelosi: "Congresswoman Giffords is a brilliant and courageous member of Congress, bringing to Washington the views of a new generation of national leaders. It is especially tragic that she was attacked as she was meeting with her constituents whom she serves with such dedication and distinction."

- House Speaker John Boehner, R-Ohio: "An attack on one who serves is an attack on all who serve. Acts and threats of violence against public officials have no place in our society."

- U.S. Sen. John McCain, R-Arizona: "I am horrified by the violent attack on Representative Gabrielle Giffords and many other innocent people by a wicked person who has no sense of justice or compassion.  ... Whoever did this, whatever their reason, they are a disgrace to Arizona, this country and the human race, and they deserve and will receive the contempt of all decent people and the strongest punishment of the law."

- Former Alaska Gov. Sarah Palin: "There is no place in our society or discourse for such senseless and unconscionable acts of violence."

THE RHETORIC

- Officials have not stated a motive for the shooting.

- Pima County Sheriff Clarence Dupnik used a nationally televised press conference to condemn the tone of political discourse in his state. He charged that public debate is now "vitriolic rhetoric," which has rendered Arizona "the mecca for prejudice and bigotry." Dupnik suggested that such rhetoric can have deadly consequences.

- Last March, Giffords raised concerns about inflammatory rhetoric after her office was vandalized, and she cited how her name appeared on a website titled "Take back the 20" as part of a list originally issued by former Alaska Gov. Sarah Palin in March 2010 against vulnerable House Democrats.

- The list, which named 20 House members who voted for health care reform, showed crosshairs over the contested Democratic districts.

- At the time, Giffords responded to the map by saying on MSNBC that her long-serving colleagues had "never seen anything like it." "The thing is, the way that she has it depicted has the crosshairs of a gun sight over our district," Giffords said in March. "When people do that, they've got to realize there's consequences to that action."

- A day after Giffords voted in favor of health care reform, a glass panel at her Tucson office was shattered.

- At a town hall meeting, a gun fell out of a constituent's pocket.

- Giffords' press secretary, C.J. Karamargin, said he was unaware of any recent threats against Giffords.