A Saturday morning report of a gunman at large at the Massachusetts Institute of Technology turned out to be false, with officials from the FBI and Secret Service announcing they had joined the investigation into the hoax.

Police in Cambridge, Mass., dispatched “all available units” to MIT at 7:31 a.m. Saturday, two minutes after receiving a tip that a man wearing body armor and carrying a firearm was seen on campus. The school grounds immediately went into lockdown, with Internet users being redirected to a school emergency page, which read the following:

“This morning information was received from Cambridge Police that there was a person with a long rifle and body armor in the Main Group Building of MIT. Multiple law enforcement agencies have responded. Stay indoors and shelter in place and report suspicious activity to the campus police dispatch at 617-253-1212 or dial 100 from a campus phone. More updates to follow.”

MIT staff was sent an email warning them to stay clear. It wasn’t long before listeners noticed very little chatter on the Cambridge police scanner. Shortly after that, police admitted they had found no one with a gun in the Main Group Building, and by 10 a.m. they said the claims were “totally unfounded.”

“An incident command was established, and a coordinated room-by-room search was conducted,” read a statement on the Cambridge police website. “No armed suspects were found in the building or on campus, and police believe that the event, as reported, did not occur. Detectives began actively investigating the report and following up on all possible leads. The investigation remains ongoing at this time.”

During a press conference on Saturday afternoon, law enforcement officials said they’re still investigating where the tip came from, although they did confirm it was received via the Internet. The Boston Globe reported that 30 police officers responded to the initial call and the MIT campus was locked down for three hours.