A Chicago man was wounded in the shooting, and many other Chicago area residents were inside LAX when the shooting happened.
Witnesses describe chaotic scene at LAX
The passengers ABC7 Eyewitness News spoke with said they could see the fear on everyone's face as they were instructed to hit the ground.
"I heard a man scream get down," said Brittany Antos, witness.
Brittany Antos of West Chicago had just landed in Terminal 3. Fearing for her life, she ran to nearest exit.
"There was sound of gunshots, sirens, helicopters, people yelling and running everywhere," said Antos.
Over in Terminal 2, Plainfield resident Sherita McDonald and 10 members of family arrived at LAX to this.
"It was very chaotic we were told there were two gunmen on the loose and we should move quickly. . . We're thankful to be alive," said Sherita McDonald. "
That is the sentiment for thousands of passengers, including Alfred Scaletta of Hawthorne Woods. He and his wife pam were traveling to LA to celebrate their daughter's birthday when their plans were interrupted.
"We saw police with rifles then me and my wife ran and hid behind a concrete barrier," said Alfred Scaletta, witness.
Scaletta says Friday's shooting brings back memories of the Boston Marathon bombing. He finished the race 30 minutes before the bomb went off. On Friday, he is once again counting his blessings.
"We feel pretty lucky nothing bad happened to us," said Scaletta.
Scaletta described the law enforcement at the scene as brave and compassionate. He and his wife did meet up with their daughter. He said Friday's incident has made him even more determined. He is planning to run the Boston Marathon again in the spring.
LAX shooting impacts flights at Chicago airports
There were bomb-sniffing dogs and officers in bullet proof vests in front of security checkpoints on Friday night, part of what Chicago aviation officials are calling a heightened state of awareness.
Word of the shooting didn't reach many Los Angeles passengers until they arrived in Chicago.
"It's absolutely terrible. It's shocking news. I'm completely stunned," said John Deeley, LAX passenger.
At O'Hare, all inbound flights from LAX terminal 3, where the shooting happened, we're canceled.
O'Hare-bound passenger Kirk Stinson says he was mere feet from the shooter.
"Everybody was scrambling in that small terminal just to try to get away. . .We were just finding anything we could to hide behind. And you couldn't know where the bullets were coming from," said Kirk Stinson, witness.
Stinson spoke to Eyewitness News by phone from a holding station at LAX, where hundreds of terminal 3 passengers were kept all day, unable up board flights.
He was to meet up with his brother Kent, who flew in from Colorado, so the two could surprise their sister at her 50th birthday party in Crystal Lake.
"We're stuck really waiting until they have an answer, and last we heard we're here for another three or four hours until they clear terminal 3," said Stinson.
"I'm thankful he's alive. When he called me I was frantic, too. I'm still kind of shaken, but thank God he's alive," said Kent Stinson, brother of stranded LAX passenger.
On Friday night, bomb sniffing dogs greeted arriving passengers, and behind the scenes, officials kept watch with a network of cameras.
TSA officers are unarmed, and unlike at LAX, City of Chicago aviation police don't carry guns.
If a similar shooting were to happen at O'Hare, the job of taking down a gunman would fall to responding Chicago police officers.
"Well that's always been a delicate discussion point for quite some time. Should the airport police at O'Hare be armed? This will spark more of that debate," said Jody Weis, Eyewitness News Public Safety Expert.
On Friday night, a government official tells ABC News not to expect any increased TSA-related security measures at checkpoints on Saturday, but local law enforcement may be more visible.