By Jane Ross
LOS ANGELES (Reuters) - Heavy security at subway stations in Los Angeles greeted commuters on Tuesday as federal and local authorities investigated a specific but uncorroborated threat to detonate a bomb at the Metro Red Line's Universal City station.
Local media broadcast footage of gun-toting deputies searching passengers' bags while bomb squad teams led bomb-sniffing dogs around stations across the Los Angeles County transit system.
Los Angeles Mayor Eric Garcetti, who boarded a train at the Universal City station himself on Tuesday, said law enforcement was prepared and asked the public to be vigilant.
"I trust the professionals that are dealing with this," Garcetti told Reuters TV. "You can never erase the threat to zero, but I want to make sure that people know we have a system that can and will respond forcefully whenever there are these threats."
Federal and city officials said on Monday they had been alerted by authorities in another country to a "specific" threat against the city's Red Line commuter rail system, prompting them to beef up security and alert the public.
"This threat is imminent, ... it is very specific," Los Angeles Police Chief Charlie Beck told an evening news conference on Monday. "But the credibility still needs to be vetted."
Law enforcement officials told the news conference the threat had been relayed to the Federal Bureau of Investigation by a law enforcement agency in another country, where the threat had originated. Officials did not identify the country.
The male caller, speaking in English, had warned authorities in that country of a potential attack on Tuesday targeting the Red Line station, which is across the street from the Universal Studios theme park, Beck said.
The caller did not threaten to carry out the attack, but said he was alerting law enforcement.
The Red Line runs between downtown Los Angeles and northern neighborhoods, including Hollywood and North Hollywood. It carries about 145,000 passengers a day as part of the city's larger transit system.
(Writing by Gina Cherelus in New York; Additional reporting by Gina Cherelus in New York; Editing by Daniel Wallis and David Gregorio)