A suspicious white powder has reportedly been sent to hotels around the site of the Super Bowl in New Jersey.

According to the Associated Press, the FBI and law enforcement authorities are investigating suspicious white powder that was mailed to at least five hotels near MetLife Stadium on Friday.

The New York Daily News has reported that letters containing the powder substance was not only sent to the hotels in East Rutherford, N.J., but also to the Midtown Manhattan office of former New York City mayor Rudolph Giuliani.

The New Jersey State Police said that the Joint Terrorism Task Force and Hazard Materials units have been dispatched to each of the locations.

The Daily News also noted that police sources have said that workers who were in the mail room at the time the letters were opened may have been contaminated.

Authorities will be conducting a thorough investigation of the sent mail. Officials made it clear since the location of the Super Bowl was announced, that they would be stepping up security efforts leading up to and during Sunday’s big game.