The Los Angeles Police Department is responding to a report that a Transportation Security Administration agent was shot at Los Angeles International Airport. A suspect is now in custody, according to a source, and the fire department reports that seven people were injured. Here are the latest details:

[Updated at 3:58 p.m. ET] TSA Administrator John S. Pistole issued a statement: "I am deeply saddened to inform you that a TSA employee was shot and killed today while on duty at Los Angeles International Airport. Other TSA employees also were injured in the shooting. ... Our thoughts and prayers go out to those who have been injured and their loved ones."

[Updated at 3:56 p.m. ET] The shooter is not a current or former TSA officer, a federal source and an intelligence source briefed by the LAPD say.

[Updated at 3:53 p.m. ET] The Transportation Security Administration seized 1,556 guns last year at airports around the country, almost double the 2007 total. Through September, the agency has seized 1,343 guns.

This week 29 firearms, 27 of them loaded, were discovered at TSA checkpoints, according to a TSA blog.

[Updated at 3:50 p.m. ET] Based on September traffic totals from LAX, it's estimated that about 177,000 passengers pass through the airport each day.

[Updated at 3:48 p.m. ET] Ronald Reagan UCLA Medical Center has admitted three males from the LAX shooting. One is in critical condition and two are in fair condition, said medical director Lynne McCullough.

She said the wounds were from "gunshot and other injuries as well," she said.

[Updated at 3:32 p.m. ET] An intelligence officer briefed by Los Angeles police tells CNN that the suspect in the LAX shooting was shot multiple times in the chest, "center mass."

[Updated at 3:30 p.m. ET] Nick Pugh told CNN affiliate KTLA he was momentarily handcuffed by police during the chaos following the LAX shooting.

Pugh was standing near the Virgin America Airlines check-in counter when he heard the gunshots.

[Updated at 3:10 p.m. ET] Almost every flight out of Los Angeles International Airport will be "significantly late," according to Gina Marie Lindsay, executive director of Los Angeles World Airports.

The airport is still accepting incoming flights, but doing so at less than half the normal rate, she said.

[Updated at 3:06 p.m. ET] "This individual was shooting as he went into the terminal," and police in the airport "didn't hesitate" to confront the suspect, said Los Angeles Airport Police Chief Patrick Gannon. He called officers' actions "heroic."

He further said that officers three weeks ago "practiced the exact scenario that played out today" during a training exercise.

[Updated at 3:03 p.m. ET] There were seven people injured, six of whom were transported to area hospitals, said acting Los Angeles Fire Chief James Featherstone.

[Updated at 3:01 p.m. ET] Los Angeles Police Chief Charlie Beck says he will not discuss the nature of the injuries or the identification of the suspect. The FBI is handling the investigation, he said.

[Updated at 2:57 p.m. ET] Los Angeles Airport Police Chief Patrick Gannon said there are "multiple" victims in addition to the suspect.

[Updated at 2:56 p.m. ET] Airport police tracked the suspect through the airport and "engaged him in gunfire in Terminal 3" before taking him into custody, Los Angeles Airport Police Chief Patrick Gannon said, adding there was only one shooter.

[Updated at 2:53 p.m. ET] The gunman had multiple clips for his assault rifle, according to a former LAPD officer, who said one TSA agent was fatally shot and another agent was shot in the leg.

Police are looking for the shooter's car in the parking lot, the former officer said.

[Updated at 2:49 p.m. ET] CNN now has two sources - an intelligence source briefed by Los Angeles police and a federal source - both of whom confirm the TSA agent was killed

[Updated at 2:41 p.m. ET] A federal source briefed by the LAPD confirmed that a TSA officer was killed in the shooting at LAX. The source cautioned that information from the scene is still preliminary.

[Updated at 2:33 p.m. ET] A local hospital released the following statement: "Ronald Reagan UCLA Medical Center received three male victims from the LAX Airport shootings. One arrived in critical condition and two are listed in fair condition."

We currently have enough blood for the situation at hand.  The hospital would appreciate it if members of the community would like to call in early next week to replenish the supply."

[Updated at 2:17 p.m. ET]  A former LAPD ranking officer provided further details of the shooting, saying the gunman approached the security checkpoint, pulled out a concealed assault rifle and shot a TSA agent before walking through the checkpoint.

It was then a police officer opened fire, wounding the gunman, the source says.

[Updated at 2:15 p.m. ET] A witness describes the popping noises and screams he heard during the incident.

[Updated at 2:12 p.m. ET] American Federation of Government Employees National President J. David Cox Sr.  issued a statement saying the union was "sickened" by news of the shooting.

"Our sincerest thoughts and prayers go out to the passengers and Transportation Security Officers killed or injured in this heinous act. Thank you to all of our brave TSOs who put their lives on the line every day to keep the flying public safe," he said.

CNN has not yet verified the condition of the TSA agent.

[Updated at 2:10 p.m. ET] "There was a guy downstairs who started shooting. One guy fell down. Panic erupted,” a witness who gave his name as Alex told CNN affiliate KTLA.

The shooter appeared to have a rifle, Alex said.

https://twitter.com/CBSLA/status/396336829772734465

[Updated at 2:01 p.m. ET] Two people were shot - one of them a TSA agent , the other the gunman, and both have been transported to local hospitals, according to a law enforcement source.

Ten shots were fired, the source said. There were roughly 100 witnesses, all of whom are being interviewed.

[Updated at 1:57 p.m. ET] The Los Angeles International Airport has confirmed, on its Twitter account, that a suspect is in custody.

The airport's post also said there are "multiple victims." Earlier, a law enforcement source close to the investigation told CNN that a suspect was shot and is in police custody.

[Updated at 1:55 p.m. ET] President Barack Obama has been briefed on the shooting at Los Angeles International Airport and will continue to be updated, but the White House had no further information at this time on what happened, spokesman Jay Carney said.

[Updated at 1:53 p.m. ET] Eyewitness Chuck Ocheret says he was at Terminal 3’s gate 30 near a food court. He thinks the gate is close to the checkpoint where the shooting happened.

“I was actually at Gate 30, just walking towards the food court. … I heard a couple of popping noises. I (turned) to look. ... There was a stampede of people coming my way and I realized something was … wrong.”

“People were screaming, ‘Run into the bathroom, get behind something,’ ” he said.

He picked up his carry-on bags, ran down a corridor, came upon the point-of-no return spot (where if you leave, you can’t get back without going through security again). The guard there didn’t appear to immediately know what was going on because he was telling people they couldn't return if they left.

Police then came and told everybody to get down on the floor. They then told everyone to go outside, and police eventually escorted them to the international terminal.

[Updated at 1:50 p.m. ET] The number of people injured is still unclear.

[Updated at 1:48 p.m ET] Kari Watson Told CNN affiliate KABC she was at LAX Terminal 3 with her 3-year-old daughter moments before gunshots rang out.

"All of a sudden we heard people screaming, 'Go, go, go!' and I heard a couple of pops that sounded like gunfire," she said. "People were just running, so we left everything on the ground and we took off."

[Updated at 1:46 p.m. ET] Witness Alex Neumann was at a food court, waiting to travel to Miami, when the incident unfolded. He said Terminal 2 was put into lockdown.

"People were running and people getting knocked down. There was luggage everywhere," Neumann told CNN. "Mayhem is the best I can describe it."

Several police officers moved about the airport with guns drawn, he said.

[Updated at 1:43 p.m. ET] A witness describes the scene after the shooting.

[Updated at 1:40 p.m. ET] A suspect has been shot and is in police custody after a shooting at Los Angeles International Airport, a law enforcement source close to the investigation tells CNN.

[Updated at 1:39 p.m. ET] There is a local media report that a large box of ammunition was found at the scene.

[Updated at 1:37 p.m. ET] "The City of Los Angeles is on Tactical Alert due to a major incident occurring at LAX," police tweeted.

[Updated at 1:34 p.m. ET] A former Los Angeles Police Department ranking officer tells CNN a shooter approached the checkpoint and shot a Transportation Security Administration agent.

Multiple shots from a rifle were fired in quick succession, and it's not clear whether the shooter breached the security checkpoint, the source said.

[Updated at 1:33 p.m. ET] "All upper/departures level roadways are temporarily blocked by law enforcement. General public are being held back at law enforcement block," LAX tweeted.

It later sent another tweet: "Other than arriving flights, flight operations have been temporarily held."

[Updated at 1:23 p.m. ET] Firefighters were laying down tarps on the street at the airport, which appear to be triage tarps. Several ambulances are at the airport, and at least one person was loaded into an ambulance.

The area around the airport was jammed with cars as police shut down access to the airport.

[Updated at 1:20 p.m. ET] A "ground stop" has been issued for planes scheduled to arrive at Los Angeles International Airport, the Federal Aviation Administration said Friday.

A ground stop means flights destined for the airport are held at their departure point, according to the FAA.

[Updated at 1:18 p.m. ET] The Los Angeles Fire Department says it is assisting with a "multi-patient incident" at the airport.

[Updated at 1:13 p.m. ET] "After the initial burst of gunfire and hiding, people started jumping over one another, jumping off chairs, pushing each other. Chaos & fear," tweeted Bill Reiter of Fox Sports.

[Updated at 1:10 p.m. ET] Passenger Robert Perez, who was getting ready to fly Virgin Air, was taking a nap in the terminal when panic erupted, he told CNN affiliate KCAL/CBS.

"I heard a popping sound, and everybody was diving for cover," Perez told the station. "The TSA said there was a shooting in the terminal and evacuate the building."

At least 100 people came down a staircase. "Everybody started to panic," Perez said.

The passengers were directed to board a bus and were taken to a smaller terminal, he told the affiliate.

[Posted at 1:06 p.m. ET] Police are responding to an incident at Los Angeles International Airport that began at 12:30 p.m. ET at Terminal 3, the airport said on Twitter.

Police earlier said evacuations are under way at the airport after reports of shots fired there.