The FBI, the Los Angeles police and sheriff's departments say they will step up security on the metro system, with an increase in uniformed and undercover officers on duty.
Bomb threats are usually checked out and tips verified before the Federal Bureau of Investigation and state security go to top alert, but there has just not been the time to decide or investigate the veracity of the called-in terror tip late on 5 December.
L.A. Mayor Eric Garcetti said that he plans to ride the Red Line at Universal City on Tuesday morning himself.
"While the credibility of the threat has not been ascertained, officials from the FBI, LASD (Los Angeles Sheriff's Department) and LAPD (Los Angeles Police Department) will address the public in an abundance of caution and to discuss enhanced patrols, precautionary measures to be taken", the statement said.
The call was made by a man speaking English who threatened an attack on the "off-ramp" at the Universal City/Studio City Red Line metro station to the north of Los Angeles, about half a mile from the Universal Studios attraction, on Tuesday.
"We're working not only with local law enforcement partners and worldwide partners but also with the private sector to make sure this information that's passed on is relevant", Fike said. Global partners with the FBI's Joint Terrorism Task Force relayed the threat and officials in Los Angeles chose to step up security while they work to determine if the threat was credible.
Los Angeles County Sheriff Jim McDonnell said the public will see an increased uniform presence, especially at transit stations, and canine explosive detection teams.
"We've been running this to ground all day long", said McDonnell. And we're asking the public to take the same precautions they would take on any other day. As far as actions we're taking, what you don't see is just as important as what you will see.
Officials repeated the mantra, "If you see something, say something", while urging people to go about their lives but to contact authorities if they notice something that doesn't seem right.