[10:22 a.m.] Authorities in Cambridge are now saying the situation is all clear.
[10:12 a.m.] Police in Cambridge, Massachusetts are checking out a report of an armed man at a building at the Massachusetts Institute of Technology. According to the school, the man is carrying a long rifle and is wearing body armor.
The school urged people to stay indoors and take shelter as police investigate.
CNN is monitoring the story as it develops. Check back for details