'MIT campus put on lockdown after possible gunman sighting'

The MIT campus was put on lockdown on Saturday after a man with a long rifle and body armor was reportedly spotted inside one of the buildings on campus, CBS reported.
A part of Mass. Ave. in Cambridge was shut down for a period of time after local police tweeted at 7:30 a.m. EST that a possible gunman was seen there.
An emergency alert sent out by the school instructed students to stay indoors, seek shelter and stay away from the Main Group Building, where the gunman was reportedly sighted.