Seven hotels near the New Jersey stadium hosting the Super Bowl received envelopes containing a suspicious white powder, but the letters appeared to be part of a hoax after early tests showed the substance at some locations was cornstarch, NBC 4 New York has learned.

A law enforcement source tells NBC 4 New York that the hotels, none of which are housing the teams playing at MetLife Stadium, received the envelopes Friday.

The substance at five locations was cornstarch, the source said. The others were still being tested, but the FBI in New York said all the letters were deemed "non-hazardous."

That includes several other suspicious envelopes discovered at nearby post offices, and a location in Manhattan.

The message in all the envelopes was similar, the source said.

The FBI in Newark said the Joint Terrorism Task Force and hazmat units responded. No injuries were reported.

The Super Bowl is Sunday.