A man wearing a Zorro costume was arrested after reports of a gunman at Los Angeles International Airport turned out to be false.

The security scare caused major delays on Sunday night, as three terminals were shut down and hundreds of people evacuated while armed police stormed the building.

Police said the reports of a gunman were spurred by "loud noises", but airport officials said it was unclear whether the person wearing the Zorro costume had any connection to the incident.

All terminals reopened about two hours after the initial reports, with dozens of flights behind schedule and huge tailbacks outside the airport.

"We were on the jetway and someone starts pushing behind us," Jon Landis, a sales representative from Boston who was boarding a flight home, told The Associated Press. "One man was frantic saying there was a shooter."

Passenger Scott McDonald said he was getting off a plane in the middle of the incident and was told by the crew to get back on.

"I've never seen passengers, just normal people, on the tarmac anywhere in the United States," he told KCAL-TV.

Douglas Lee, who was traveling home to Albuquerque with his wife and son, said the greated danger was being trampled.

"You can imagine hundreds of adults trying to go through an exit door onto the tarmac," he explained.

Leyna Nguyen, an anchor for KCAL whose flight happened to arrive just before the panic began, said even false reports "create such a chaotic scene, it's really scary."

"I saw people running faster than I've ever seen people run just to get out of the way," Nguyen said.

It came just days after another false alarm led to an evacuation of Kennedy Airport in New York.

In that incident, police were investigating whether an overly boisterous celebration of the Olympics on August 14 led to noises that were misinterpreted as gunfire.