Los Angeles ? 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.

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.

“We just can’t take a risk knowing that one bad guy can harm our country significantly,” said U.S. Customs and Border Protection spokesman Mike Fleming.