The FBI and Los Angeles law enforcement agencies held a news conference this evening to announce they will be ramping up security for the city’s Metro rail system Tuesday after an anonymous tipster warned that the Metro Red Line station nearest NBCUniversal’s sprawling Universal Studios Hollywood complex would be attacked.

Officials said the threat was considered “specific and imminent,” and decided to make it public because they had little time to vet the threat as they do others. They said to expect an increased security presence of uniformed LAPD and LA County Sheriffs officers at stations and on trains, as well as bomb-sniffing dogs. Los Angeles County Sheriff Jim McDonnell said undercover operations would be ongoing throughout the day.

The FBI said the tip came from its international partners but that it was still being determined if the threat was credible or whether it is a hoax.

Universal City is home to the theme park, which now includes the holiday-themed Grinchmas installation as well as the new Wizarding World Of Harry Potter which opened in April. The 391-acre area parcel also includes Universal Studios, Universal CityWalk and the West Coast offices of NBCUni.