LOS ANGELES (AFP) - An anonymous bomb threat against the Los Angeles metro appears to have been a hoax, officials said late Tuesday (Dec 6) after a heightened alert lasting much of the day.
Police deployed in force throughout the system following a tip from overseas about an imminent attack on a busy station near the Universal Studios theme park.
But Tuesday night the Federal Bureau of Investigation said in a statement there was "no evidence" of a threat to the city's metro system.
"Working with our law enforcement partners, the FBI has found no evidence that the threat made to the Los Angeles Metro Red Line is credible," the bureau said.
"Based on significant similarities, law enforcement partners also believe the anonymous caller may have, on a previous occasion, reported threats that did not materialise."
Last year an emailed threat forced the closure of Los Angeles schools for a day before it was determined to be a hoax.
Throughout the day on Tuesday about a dozen officers, some in full tactical gear and accompanied by sniffer dogs, patrolled the Red Line's Universal City metro stop, where an anonymous phone caller warned that a bomb would go off.
The man, who spoke English, relayed the threat in a telephone call early Monday to a public safety line run by an unidentified foreign government, which passed on the information to the FBI's terrorism task force.
The threat prompted authorities to hastily organise a news conference late Monday to relay the information to the public and announce that security was being stepped up.
In a bid to allay fears, Los Angeles Mayor Eric Garcetti rode the metro from Universal City early Tuesday. Orange barriers were put up around the station as police randomly searched people's bags.
Some commuters appeared unnerved by the added patrols while others went about their normal business.
Some 145,000 people use the two main lines of the Los Angeles metro. The Red Line connects North Hollywood with central and downtown Los Angeles.
Even though authorities said they no longer believe a threat exists, they urged Los Angeles residents to stay vigilant and said stepped-up patrols would continue.