Updated, 9:00 p.m.
One Transportation Security Administration employee was killed and others were wounded Friday in a shooting at Los Angeles International Airport.
The suspected gunman is Paul Anthony Ciancia, police said, a 23-year-old resident of LA who appeared to have no direct connection to the TSA. He had "anti-government materials" on him at the time, said NBC News Pete Williams.
Witness Leon Saryan told reporters that the gunman approached him, asked "TSA?" and when Saryan said no, the gunman moved on (see video above).
The exact chronology of the attack remained unclear, but it seemed that Ciancia approached the TSA document checker by walking through an "exit" lane, the path used by passengers who are leaving the secure area of the airport. Officials said he pulled an assault rifle from a bag and opened fire.
Mayor Eric Garcetti said airport police responded to the gunfire, followed the suspect and shot him as he was continuing to fire. The police said one person had been arrested. Ciancia's condition was unknown.
“We’re not going to be able to tell you a lot of things you might want to know, but this is ongoing,” Mayor Garcetti said.
Seven people were injured in the incident, and six were brought to local hospitals, according to Jim Featherstone, general manager of the LA Emergency Management Department.
LAX is the world's sixth busiest airport and the third busiest in the country. There was a "ground stop" in place for the airport for several hours, with flights bound for LAX being held. In all--including those due to arrive or depart from the airport, and those whose flights were diverted--about 76,000 passengers were affected by the incident.
The TSA's union, American Federation of Government Employees, said in a statement that it was "sickened" by reports of the shooting. "Our sincerest thoughts and prayers go out to the passengers and Transportation Security Officers killed or injured in this heinous act," the group's president, J. David Cox Sr., said, adding, "AFGE is monitoring the situation along with TSA management."
The White House said President Obama was briefed on the shooting. "We will continue [to] stay in touch with our federal and local partners," a White House official said in a statement. "We urge citizens to listen to the authorities and follow directions from the first responders on site. The president will continue to receive briefings throughout the day."
NBC News' Pete Williams and affiliate KNBC contributed to this report.