Airlines struggled to clean and refuel planes where passengers had been trapped for hours because of a computer crash, leading to additional delays Sunday at Los Angeles International Airport.

Mayor Antonio Villaraigosa called for an investigation as carriers dealt with the fallout from Saturday’s computer crash, which stranded more than 20,000 inbound travelers in the terminal and on planes.

At least four outbound international flights were delayed for an hour or more, according the airport’s Web site.

One Zurich-bound Swiss International Air Lines plane was expected to depart at around noon Sunday, some 14 hours after its scheduled departure time, airline spokeswoman Andrea Kreuzer said.

“We were not able to prepare the aircraft,” Kreuzer said.

Thousands of passengers were kept on planes or in airport terminals after customs department computers containing travelers’ identities and law enforcement records went down, preventing authorities from screening people arriving in the U.S.