LOS ANGELES (CBSLA.com) — A TSA agent was killed and six people were injured Friday in a shooting at Los Angeles International Airport, police said.

The gunman entered Terminal 3 at 9:20 a.m. and opened fire, officials said. Law enforcement authorities identified him as Paul Anthony Ciancia, 23, who has lived in the Los Angeles area for 1 1/2 years but is originally from Pennsville, N.J.

Preliminary information suggests he was targeting TSA employees. CBS2’s Randy Paige said Ciancia shot two people; both were TSA officers, and one of them died. Friday night, the TSA identified the slain officer as Gerardo I. Hernandez, 39; he is the first TSA officer killed in the line of duty in the agency’s 12-year history.

According to Chief Patrick Gannon of Los Angeles World Airports, the suspect pulled an assault rifle — possibly an AR-15 — out of his bag, started shooting and proceeded to the TSA screening area, where he was able to gain access to the airport itself.

PHOTOS: Shooting At LAX

Security officers followed the man, engaged in gunfire with him, and were subsequently able to take him into custody, Gannon said. Ciancia was wounded, Paige reports, but authorities have released no details on his condition or his motive.

Sources tell CBS News, however, that Ciancia had anti-government views. The Associated Press said the alleged gunman had a hand-written note with him that said he “wanted to kill TSA and pigs.”

CBS2’s David Goldstein reports that Ciancia sent a text message to a family member in New Jersey early Friday in which he threatened to kill himself. His father called local police in New Jersey, who called Los Angeles police. According to the local police chief, the LAPD sent a car to his apartment. His two roommates said they hadn’t seen him since Thursday and that he was fine.

Rachel Kim, reporting for CBS2, said Ciancia has no criminal background.

She spoke to a restaurant owner that said Ciancia frequented his place, Morrison Gastro Pub in Los Feliz.

“I would never have suspected that he would be that guy today,” said Marc Kreiner. “He was very quiet, very respectful. He would acknowledge me, he’d put his hand out and shake my hand. And I would see him on the street walking, I guess he lived over here, but I was just torn apart when I heard what happened.”

Police are confident that the gunman acted alone. But authorities who searched the airport after the shooting found a large box of ammunition. An LAPD bomb squad and tactical team swept the terminal and evaluated baggage, according to CBS News.

RELATED: Who Is Paul Ciancia?

Hernandez, 39, of Porter Ranch, was taken to Harbor-UCLA Medical Center in Torrance, where he was pronounced dead, KCAL9’s Stacey Butler reported. The union that represents TSA officers said Hernandez was a behavior detection officer who had recently transferred from Montana.

At least six other people were injured and treated at the scene. Two of them were taken to Harbor UCLA — Hernandez, who died, and another person who suffered a minor shoulder wound. That person was expected to be released from the hospital soon, Butler reported.

Three people were taken to Ronald Reagan UCLA Medical Center in Westwood, KCAL9’s Serene Branson reported. One was released from UCLA Medical Center shortly after 3 p.m., according to hospital officials. Two others patients remained at the hospital, one in critical condition and another in fair condition.

Branson says one of the wounded was identified by family members as Brian Ludmer, 29, a theatrical technical director at the Las Virgenes Unified School District.

The district superintendent told Branson that Ludmer had been with the district for more than a year.

RELATED: Neighbors Mourn TSA Agent Killed In LAX Shooting

The airport partially reopened at 1 p.m. By Friday night, Terminals 1 and 2 were open, but Terminal 3 remained cordoned off. The airport announced on its Twitter account that the upper and lower roadways around the airport had reopened to all cars.

All terminals except for T3 are now open. Upper/Departures & Lower/Arrivals roadways are now open to all cars. Thank u for your patience! — LAX Airport (@flyLAXairport) November 2, 2013

The shooting created in chaos in the bustling terminal. Passengers ran through doors and onto the Tarmac to escape the gunfire.

“We just started running,” one woman said. “And we went downstairs and out onto the Tarmac, and we’re running under the airplanes, and TSA is running with us at the same time.”

Passenger Robert Perez told CBS2 that TSA agents came through the terminal and yelled about a man with a gun.

“I heard popping and everybody dropped to the ground,” Perez said.

RELATED: Passengers At Terminal 3 Recount Stories Of Fear, Terror

Another witness said he actually saw the alleged shooter.

“I was waiting for my flight and heard a rumble of people, which I thought was an earthquake, but then I saw people running and heard gunshots, immediately dove under the benches at my gate, and then gunshots stopped and I got up and called my wife,” Billy Bey said. “Then I saw a man walking towards the gate, when I saw him I thought he was just a passenger looking for his gate, but when he kept walking, I saw he had something looked like an assault rifle, a huge gun strapped over his shoulder, hanging down on the right side of his waist.”

Passenger Rodrigo Jara told KNX1070 NEWSRADIO he was waiting in line to go through the security line in Terminal 3 when he heard a loud sound.

“I heard ‘pop, pop, pop,’ and then we fell down, and little did I know, I looked to the side, and this guy’s going up the stairs with the rifle,” Jara said.

Jara described the shooter he saw as a white male with blonde/dirty blonde hair possibly wearing khakis, clean-cut, and “walking like he was going to buy tea.”

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Airlines serviced at Terminal 3 include AirTran, Alaska, Horizon, JetBlue, V Australia and Virgin America.

Virgin America employees were able to lock themselves, as well as travelers, in a room until authorities deemed the area safe.

LAX officials said people who had abandoned personal belongings in Terminal 3 or Parking Structure 3 might be able to pick them up Saturday evening. The American Red Cross was providing cots and basic necessities for stranded passengers, the airport tweeted.

American Red Cross is providing cots & basic necessities in TBIT for displaced passengers. Mental Health providers available as needed — LAX Airport (@flyLAXairport) November 2, 2013

About 800 flights were canceled Friday at LAX, with 76,000 passenger affected.

The shooting also affected incoming flights. With the airport closed and runways empty, some incoming flights were diverted to the Ontario airport. But passengers weren’t necessarily told where they were going.

“They came on the PA and they just started with, well, we’re in California, and usually that’s not what they say when we land in the right place,” passenger Elysa Berg told CBS2.

No flights were diverted to Bob Hope airport in Burbank or John Wayne Airport in Orange County. Those airports continued normal operations, with an increase in security.

RELATED: SoCal Airports Beef Up Security After LAX Shooting

The FBI will be a lead agency in the investigation. It will be aided by the LAPD, LA Airport police and the U.S. Attorney’s Office.

J. David Cox Sr., the head of the union that said union officials were “sickened” by the shooting.

“Our sincerest thoughts and prayers go out to the passengers and Transportation Security Officers killed or injured in this heinous act,” Cox said. “Thank you to all of our brave TSOs who put their lives on the line every day to keep the flying public safe. [The American Federation of Government Employees] is monitoring the situation along with TSA management.”