A man armed with what police say was an assault rifle and carrying materials expressing anti-government sentiment opened fire Friday morning at Los Angeles International Airport, killing one person before being chased down himself, authorities said.
Eyewitnesses said the suspect asked people, "Hey, are you TSA?" -- the acronym for the Transportation Security Administration -- according to a federal law enforcement official. If they said "no," he would move on.
One of those questioned travelers was Leon Saryan. He told CNN's Anderson Cooper that the same man he'd just seen shoot a TSA officer "calmly" walked toward him and asked, "TSA?"
"I just shook my head," Saryan said. "And he kept going."
In the aftermath of the shooting, investigators found information on the suspect expressing not just anti-federal government sentiment but also anger at the TSA specifically, according to the federal law enforcement official.
By then, a TSA officer was dead -- the first employee of that relatively new agency to be killed in the line of duty. The agency identified him as Gerardo Hernandez, who would have turned 40 next week. He was working as a travel document checker at the time of the shooting, according to TSA workers' union and federal sources.
Two additional TSA officers were also shot, one in the leg, authorities said.
The suspected gunman himself was detained after being shot in the chest multiple times, according to an intelligence source briefed by Los Angeles police. As of Friday evening, he was receiving medical attention at a hospital, according to FBI Special Agent in Charge David Bowdich.
He was identified later by the FBI as Paul Anthony Ciancia, a 23-year-old from Los Angeles. He graduated in 2008 from Salesianum School, an all-boys Catholic school in Wilmington, Delaware, according to school President Brendan P. Kennealey.
The intelligence source said Ciancia's family became concerned in recent days after he sent his brother and father "angry, rambling" texts venting about the government, living in Los Angeles and his unhappiness generally.
Ronald Reagan UCLA Medical Center said that it received three male victims -- one in critical condition and two in fair condition. One of the two in fair condition suffered gunshot wounds, while another had an unspecified injury, said Dr. Lynne McCullough, an emergency physician at the Los Angeles hospital. One of them was released by Friday afternoon; one of the others who remained at the hospital was Ciancia, according to the intelligence source.
Two patients, meanwhile, were transported to Harbor-UCLA Medical Center in Torrance, said David Klurad, a trauma surgeon there.
One was what Klurad described as a "middle-aged" person with minor injuries from being shot in the shoulder. The other had no signs of life when he arrived at the hospital, the surgeon added. It wasn't known if this person was the slain TSA officer.
The episode caused what airport police Chief Patrick Gannon, who had said the shooter used an "assault rifle," described as a "large amount of chaos." People ran for their lives and took shelter wherever they could as authorities pursued the gunman.
Chuck Ocheret was among those in the busy airport when he heard two "loud pops."
"Then I heard this mad rush of people, and there was a stampede of people coming from this direction," Ocheret told CNN. "Nobody really knew what was going on."
Still, by Friday afternoon, authorities believes the worst was over. Gannon noted it is believed there was only one shooter.
Suspect 'pulled an assault rifle out ... and began to open fire'
An otherwise normal day in the airport's Terminal 3 turned upside down around 9:20 a.m. (12:20 p.m. ET), as the suspect approached a checkpoint.
There, he "pulled an assault rifle out of a bag and began to open fire," Gannon said.
Passenger Saryan had just cleared the TSA checkpoint and was reaching for his shoes and belt when shots rang out, prompting "everybody (to) hit the ground and .. run." A TSA officer grabbed Saryan's shoes and started running alongside him, before the gunman grazed the officer with a bullet.
"I went and cowered in a corner," Saryan said.
The suspect kept moving down Terminal 3, equipped with three magazines for his weapon, according to the intelligence source briefed by Los Angeles police, he began running down Terminal 3.
He had company. Gannon said two officers from his department responded "within seconds after the shooting started" and ran off in pursuit of the suspect.
Traveler Vernon Cardenas was sitting at one end of the terminal, when he heard noise and saw a mass of people running toward him. He and others bolted through a kicked-open exit door and ran onto the tarmac -- believing then it was safer there -- even with then still-arriving and departing jetliners -- than in the terminal above.