A gunman opened fire with an assault rifle at Los Angeles International Airport (LAX) Friday, killing a security agent and wounding seven people, AFP reports citing officials.
Panicked travelers scrambled to escape after the lone suspect, named as 23-year-old Paul Anthony Ciancia, pulled out the gun and shot his way through a security checkpoint before being stopped in an exchange of fire with police.
The motive for the shooting was unclear, but the Federal Bureau of Investigation said it could not rule out terrorism. The gunman was reported to be in critical condition in hospital.
The shooter "came into Terminal Three, pulled an assault rifle out of a bag and began to open fire... He proceeded up into the screening area... and continued shooting," said LAX police chief Patrick Gannon.
He then entered the main terminal area and reached a Burger King restaurant before officers "engaged him in gunfire... and were able to successfully take him into custody."
The Transportation Security Administration (TSA), which employs screeners and guards at airports, confirmed one of its employees had died.
"Multiple Transportation Security Officers (TSOs) were shot, one fatally," said a TSA statement emailed to AFP.
The Los Angeles Times initially cited sources saying the shooter, who opened fire shortly after 9:00 am in the crowded terminal was also believed to be a TSA employee at the airport, which is the country's third-biggest hub.
Gannon would not comment on that report, but said: "We believe at this point that there was a lone shooter," and that he "was the only person who was armed in this incident."
Later, the FBI named him as Ciancia, saying he was a LA resident but giving no further details.
An NBC television report suggested Ciancia may have had some link to the TSA, and targeted TSA agents as his victims.
Of the seven people injured, six were taken to hospital, said the head of the LA Fire Department James Featherstone, briefing reporters for the first time a couple of hours after the incident.
One eyewitness recounted the shooter dressed in greyish-green clothing with an assault rifle opening fire as he went up an escalator and through the security area.
Live television footage showed armed police on the top of parking structures, apparently still looking for a possible gunman, while multiple ambulances were parked outside a terminal building.
Flights were disrupted as the Federal Aviation Administration (FAA) issued a national ground-stop, or hold, for all LA-bound flights that had not yet departed from their originating airports.
Eyewitness Brian Adamick, 43, said he was preparing to board a flight when he saw people running through the terminal, away from a security area. He and others responded by going through an emergency exit onto the tarmac.
A short time later shuttle buses began helping passengers to leave and he saw a wounded airport worker, from the TSA, board one bus, with a bloodied ankle.
"It looked like it was straight out of the movies," said Adamick.
Another non-US passenger, named only as Alex, said he was waiting in line on an upper terminal level when the shooter opened fire on the floor below.
"He shot one guy downstairs," he told KTLA 5, adding that the gunman then went up some escalators toward a security area.
"He fired several shots when he went through the security check," he said, adding: "He just went straight through the security check."
Eyewitness Eric Williams described the gunman to ABC7 television.
"We were standing in the TSA line to get checked through and all of a sudden we heard a shotgun. I saw the shooter and he was a Caucasian probably 18 to 25 years old," he said.
Although there was no indication of other people being involved in the attack, the FBI said it could not rule out terrorism.
"It would be premature to comment on a motivation at this time and joint investigators have neither ruled out terrorism, nor ruled it in," it said.
In Washington, President Barack Obama was kept up to date on the shooting. "Obviously, we've been monitoring it and we're concerned about it," Obama said.
By Michael Thurston