(CNN) -- A person with a firearm at Los Angeles International Airport approached a checkpoint at Terminal 3 and opened fire Friday morning at a Transportation Security Administration agent, a former Los Angeles Police Department ranking officer who was at the scene told CNN.
[Original story, posted at 1:21 p.m. Friday]
Reports of gunfire Friday morning at Los Angeles International Airport prompted evacuations of portions of LAX and led to a "ground stop" for arriving planes, said police and the Federal Aviation Administration.
No further details were immediately available on the gunfire, police said.
Airport officials said a police incident began about 9:30 a.m. at Terminal 3 at LAX, airport spokeswoman Nancy Suey Castles said.
Passenger Robert Perez, who was getting ready to fly Virgin Air, was taking a nap in the terminal when panic erupted, he told CNN affiliate KCAL/KCBS.
"I heard a popping sound, and everybody was diving for cover," Perez told the station. "The TSA said there was a shooting in the terminal and evacuate the building."
At least 100 people came down a staircase. "Everybody started to panic," Perez said.
Fox Sports national columnist Bill Reiter was also at the airport during the gunfire. "After the initial burst of gunfire and hiding, people started jumping over one another, jumping off chairs, pushing each other. Chaos & fear," he said on his Twitter account.
The passengers were directed to board a bus and were taken to a smaller terminal, Perez told the affiliate.
Alex Neumann was at a food court, waiting to travel to Miami, when the incident unfolded. He said Terminal 2 was put into lockdown.
"People were running and people getting knocked down. There was luggage everywhere," Neumann told CNN. "Mayhem is the best I can describe it."
Several police officers moved about the airport with guns drawn, he said.
The Los Angeles Fire Department is assisting with a "multi-patient" incident at Los Angeles International Airport, the department said Friday on Twitter.
Firefighters were laying down tarps on the street at the airport, which appeared to be triage tarps. Several ambulances were at the airport, and at least one person was loaded into an ambulance.
The area around the airport was jammed with cars as police shut down access to the airport Friday morning.