At Long Beach, "they are treating it as a non-specific, non-credible threat at the moment ... although the airport is being swept by canines," a spokesman for the Department of Homeland Security said.
"Eight flights are affected. They normally open at 5 am (0800 EDT/1200 GMT) but they are now probably going to start opening between 7 am and 8 am," the spokesman said.
Officials could not give any additional details on the nature of the bomb threats.