LOS ANGELES — About 2,500 international passengers were stranded for as long as five hours Saturday on planes and in terminals at Los Angeles International Airport because a computer shutdown prevented them from passing through customs, authorities said.

The passengers were stranded in four airport terminals and on runways starting at about 1:30 p.m. because of a breakdown in a computer system that contains names of arriving passengers and law enforcement data about them including arrest warrants, said Mike Fleming, a Customs and Border Protection spokesman.

"That system allows our officers to make decisions on who we can allow to enter the United States," Fleming said. "You just don't know by looking at them."

The cause of the shutdown was not known, and there was no estimate on when the system would be repaired, Fleming said.

Authorities had begun using a backup system by 7:45 p.m. and were processing passengers in order of their arrival.

However, the system could only support half of the inspection booths normally used by customs officers, Fleming said.

Customs officials were working to divert incoming flights to airports in Ontario, Calif., and Las Vegas, Fleming said.

Terminals that normally accept international passengers have been full since at least 2:30 p.m., and passengers arriving since then have had to remain on the runway.

"This is just unbearable," said Gaynelle Jones, 57, who landed on a 13-hour flight from Hong Kong at about 2:15 p.m. and was still sitting on her plane five hours later. She said she had missed her connecting flight to Houston.

"We've already been on a plane for several hours, and they have no timeframe for when we'll be able to get off," Jones told The Associated Press from her cell phone.