UPDATE: CAMBRIDGE, Mass. (AP) - Police in Mass. say after search that reports of gunman on MIT campus are unfounded.

Earlier:

BOSTON (AP) - The Massachusetts Institute of Technology says a man carrying a long rifle and wearing body armor was spotted in a campus building, and the school is on lockdown.
    
MIT said in a statement Saturday that several law enforcement agencies have responded, and a photo that appears to have been tweeted from near campus shows a road blocked to traffic.
    
The school advises students and workers to stay indoors and report suspicious activity to campus police.
    
More details were not immediately available.

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