A 23-year-old man wielding an assault rifle and carrying 100 rounds of ammunition shot and killed a Transportation Security Administration officer at Los Angeles International Airport on Friday morning, sending travelers fleeing in panic and paralyzing one of the world’s busiest airports for hours.
Two other people, one of them a security agent, were shot and at least four others were injured in the melee.
The gunman entered Terminal 3 just before 9:3o a.m., pulled a weapon from a bag and began firing as he forced his way through a security checkpoint, officials said. Airport police officers chased him through the bustling terminal as he continued to fire, before shooting him near a departure gate and arresting him.
The T.S.A. agent who was killed was the first to die in the line of duty since the agency was created in the aftermath of the Sept. 11 terrorist attacks, officials said.
Thousands of travelers throughout the airport were evacuated and flights were grounded for hours, with some incoming flights diverted to nearby airports and others held on the tarmac while the shooting unfolded. Passengers spent hours in waiting areas, parking lots and nearby hotels as they waited for flights to resume. Air traffic across the country was stalled in a ripple effect from the shutdown.
Federal officials identified the gunman as Paul Ciancia of Los Angeles, who had previously lived in New Jersey. A senior federal official said that he had a note with “antigovernment and anti-T.S.A. ramblings.” Mr. Ciancia was being treated at a Los Angeles hospital, officials said.
Former classmates at the Salesianum School, a private boys’ school in Wilmington, Del., said Mr. Ciancia was a quiet student. He played the tuba in the school band for all four years he attended, 2004 to 2008, said Jesse Sooy, 23.
“He was a really quiet kid,” Mr. Sooy said, describing a slight young man, no taller than 5-foot-7, with dark brown hair, who rarely spoke unless spoken to. “His dream was to work in his dad’s collision company,” Mr. Sooy said, naming it as Salem County Collision, an auto repair shop in Pennsville, N.J. “I was so shocked that he was even at LAX.”
In Pennsville, neighbors of the Ciancia family described them as hard-working people who had lived in the community for at least 20 years and kept to themselves.
“Paul, the father, has been a well-respected businessman here for many years, and has always taken care of people well,” said Gary Hankins, who lives across the wooded street in the suburban South Jersey community of about 14,000.
Rich Garry, 68, of Fullerton, Calif., said he had been at Terminal 3 on Friday morning headed for a flight to New York to visit family members. He said that a security officer had just checked his boarding pass and that he was waiting in line at the security checkpoint when he heard two shots.
“I heard a ‘pop-pop’ and I looked down a floor below, and the T.S.A. guy was on the floor,” he said. “He had been shot.”
Mr. Garry said he believed it was the same security officer who had inspected his boarding pass.
As the gunman moved through the terminal, Mr. Garry said, “he was very calm. When he got to the top of the stairs where the security checkpoints are, he looked around. If he would have come up the ramp, he would have had a field day with all the people lying on the ground, like me.”
Mr. Garry said he and several others crawled to a nearby elevator and went to the ground floor. Once there, he saw police officers for the first time, and told them to go to the second floor.
