"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," the school said in an emergency statement issued to its student body, staff, and faculty, according to WCBV Boston.
"Multiple law enforcement agencies have responded, stay indoors and shelter in place and report suspicious activity to the campus police dispatch dial 100. More updates to follow."
The man was reportedly spotted around 7 a.m., wearing body armor and carrying a long rifle, according to the Associated Press.
Cambridge police searched the area and found no one matching the suspect's description, tweeting:
Scene is clear. Call unfounded. No threat to public safety in #CambMA #MIT
Police officers shut down part of Massachusetts Avenue, which runs through the MIT campus, and searched a building room by room where he was thought to have entered, CBS Boston reported.