Pedestrians on the MIT Campus in Cambridge, Mass., duck underneath police tape, Saturday, Feb. 23, 2013, after police responded to reports of a gunman on campus that Cambridge police later said were unfounded. Police said that officers searched for a man reported to be carrying a long rifle and wearing body armor and found nothing. A spokeswoman for the university says the school also called off a campus-wide lockdown. (AP Photo/Josh Reynolds)

Pedestrians on the MIT Campus in Cambridge, Mass., duck underneath police tape, Saturday, Feb. 23, 2013, after police responded to reports of a gunman on campus that Cambridge police later said were unfounded. Police said that officers searched for a man reported to be carrying a long rifle and wearing body armor and found nothing. A spokeswoman for the university says the school also called off a campus-wide lockdown. (AP Photo/Josh Reynolds)

Pedestrians on the MIT Campus in Cambridge, Mass., duck underneath police tape, Saturday, Feb. 23, 2013, after police responded to reports of a gunman on campus that Cambridge police later said were unfounded. Police said that officers searched for a man reported to be carrying a long rifle and wearing body armor and found nothing. A spokeswoman for the university says the school also called off a campus-wide lockdown. (AP Photo/Josh Reynolds)

Pedestrians walk by police tape on the MIT Campus in Cambridge, Mass.,after police responded to reports of a gunman on campus that Cambridge police later said were unfounded, Saturday, Feb. 23, 2013. Police said that officers searched for a man reported to be carrying a long rifle and wearing body armor and found nothing. A spokeswoman for the university says the school also called off a campus-wide lockdown. (AP Photo/Josh Reynolds)