An overseas tip about an imminent bombing of the Metro Red Line's Universal City station has forced federal and local law enforcement in Los Angeles to swiftly ramp up security across its sprawling transit system, authorities said Monday.
An anonymous man warned of a potential attack on Tuesday and provided the information on a tip line abroad, according to Deirdre Fike, the assistant director in charge of the FBI's office in Los Angeles.
The tip line was run by an unidentified foreign government, which relayed the information Monday morning to an FBI terrorism task force. Fike declined to specify from which country the tip originated but said it was delivered in English.
At a hastily called news conference Monday night, the FBI as well as Los Angeles-area law enforcement leaders said the threat was considered specific and imminent, but investigators were still examining its credibility.
"This could be real, it could be a hoax," said Los Angeles County Sheriff Jim McDonnell. "We're asking the public to stay calm and vigilant."
Los Angeles Police Chief Charlie Beck said that area law enforcement reviews threats "constantly" but that this particular incident was "very specific" and forced a rapid response.
"We don't have the time to vet this threat in the way we would like," Beck said. "This one we had to move quickly on."
Riders were told to expect the increased presence of uniformed police and sheriff's deputies as well as K-9 units scouring the area for explosives.
McDonnell, whose department oversees security for the Los Angeles County Metro rail and bus system, said undercover operations would be conducted throughout the day.
Mayor Eric Garcetti asked the public to prepare for random bag searches, and said he would ride the Red Line on Tuesday morning from Universal City.
"My advice is right now, everyone should go about their normal day tomorrow," Garcetti said. "People may see a heightened security presence … but don't let those frighten you."
Nearly 150,000 daily boardings are recorded on the Red Line, which connects North Hollywood with central and downtown Los Angeles, according to the Los Angeles County Metropolitan Transportation Authority. That figure include ridership estimates for the Purple Line, which shares much of the Red Line's downtown L.A. route.
Chief Scott Edson, who oversees counter-terrorism as head of the Sheriff's Department's Homeland Security Division, cautioned that the department often receives threats and that it's hard to determine the credibility. He said passengers should report any suspicious activity.
Last year, a phone threat of violence at L.A. schools prompted the district to cancel classes for the day. Officials later determined the threat was not credible, and there was some debate about whether the district overreacted.
Times staff writer Matt Hamilton contributed to this report.
8:30 p.m.: This article was updated with additional details on the origins of the threat as well as ridership figures for the Red Line.
6:45 p.m.: This article was updated with additional details from federal and local law enforcement about the nature of the threat.
5:45 p.m.: This article was updated with background on the LAUSD incident.
5:05 p.m.: This article was updated with information about a news conference.