CAMBRIDGE (CBS) – A hoax report of a person with a “long rifle and body armor” spotted inside a building on the MIT campus put the school on lockdown Saturday morning, according to Cambridge and MIT police.

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WBZ NewsRadio 1030’s Kim Tunnicliffe reports

Cambridge police say they received the tip at 7:28 a.m. through their electronic messaging system about a man with a gun inside the Main Group Building at 77 Massachusetts Avenue.

MIT officials were immediately notified about the possible threat. All available MIT officers responded to the building, along with State and local police. Authorities say they had the building and immediate surrounding area locked down and secured by 7:43 a.m.

According to officials, an emergency alert from the school warning students to stay indoors and seek shelter was not sent out until 8:52 a.m.

“MIT would have to take responsibility for that slow down, but I think the focus was on trying to find out if, in fact, we had a situation,” said John DiFava, MIT’s Chief of Police.

DiFava added that officials are looking into why it took so long for the school to send out that emergency alert to students and staff.

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“At the conclusion of the ongoing investigation, MIT Police and other parts of the MIT administration will, as part of standard operating procedure, conduct an after-action review of MIT’s police and communications actions during this event,” the school said in a statement released Saturday afternoon.

During the lockdown, part of Mass. Ave. was shut down as officers searched the building where the possible gunman was reported.

They did not find anything, and the original tip was determined to be a hoax.

“The incident that was reported did not take place. I just want to be very clear about that,” Cambridge Police Commissioner Robert Haas said.

Police cleared the scene at 10:30 a.m. MIT lifted the lockdown about 45 minutes later.

Cambridge police say that the FBI and Secret Service have both joined the investigation into the incident. Officials say they do have some leads in the case.

“Any time you cause this kind of alarm…it has serious consequences, as you saw this morning,” Commissioner Haas said.

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If they are able to determine who sent the hoax tip, they plan to press charges.