Airlines struggled to clean and refuel planes where passengers had been trapped for hours because of a computer crash, leading to additional delays for a second day at Los Angeles International Airport.
Los Angeles Mayor Antonio Villaraigosa called for an investigation on Sunday 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 on Sunday, the airport's Web site stated.
One Zurich-bound Swiss International Air Lines plane was expected to depart around noon on Sunday, some 14 hours after its scheduled departure time, airline spokeswoman Andrea Kreuzer said.
"We were not able to prepare the aircraft," Kreuzer said.
Customs department computers containing travelers' identities and law enforcement records went down, preventing authorities from screening people arriving in the US.
"We just can't take a risk knowing that one bad guy can harm our country significantly," US Customs and Border Protection spokesman Mike Fleming said.
On Sunday, international flights were arriving on time and travelers coming to the US were making it smoothly through the airport's checkpoints, Fleming said.
It took officials until around 4am on Sunday to finish processing the backlog of incoming passengers.
"This is the Third World," said Irish tourist Caroline O'Rourke, who spent six hours on the tarmac after her 12-hour flight. "This is just disgraceful."
Three people were transported to local hospitals after they fell ill while waiting in the terminals, the Los Angeles Fire Department reported.
Airport officials said the stranded planes were connected to ground power and passengers had access to food, water and bathrooms during the hours it took to repair the computer system.
"We've had outages in the past, but they haven't taken nearly as long to resolve," Fleming said. "This was unprecedented in terms of impact."