According to LAX, a report was made at around 7:30 p.m. about a person with a firearm in Terminal 1.
Police rushed to the scene and detained two people. The airport said no shots were fired and no weapons were recovered.
About 300 passengers evacuated from the terminal onto the airfield. LAX said as they were getting out, two people sustained minor to moderate injuries and were treated by the Los Angeles Fire Department.
A third person was sent to the hospital.
Video captured by AIR7HD showed the passengers lined up along a wall near the taxiway.
As of Thursday at 8:53 p.m., the south side of the airfield was open to flights, but the north side remained closed.
One passenger spoke with ABC7 Los Angeles shortly after the incident and claims a pilot told travelers someone believed they saw a gun and yelled, "Gun!"