Unconfirmed reports of gunshots, later described by police as just “loud noises”, sparked evacuations at Los Angeles airport.
People fled the airport on Sunday night amid the shooting reports, with scenes of abandoned luggage on pavements.
Traffic to the terminal was halted and no flights were allowed to land, but operations then resumed.
The police and fire departments had deployed many units to the Los Angeles airport after reports of a “security situation” and a possible “active shooter”.
Police later said that no shots had been fired and there were no injuries. They are investigating the noises.
The airport tweeted that an individual in a “Zorro” costume had been detained.
Footage on social media showed the man sitting on a bench at a bus bay outside the airport, surrounded by armed police.
It was unclear whether he was responsible for the noises.
The incident follows another case of panic at a US airport, when parts of New York JFK airport were shut two weeks ago amid reports of gunfire that later proved to be false.