UPDATE: Footage of shootout:
UPDATE: Police confirm that "Suspect 2" (white cap) in the marathon bombing is still at large. A second suspect has been shot, apparently killed after firefight with police in which the suspect used grenades, possibly pressure cooker bombs.
UPDATE: Following a firefight and explosive detonations, the Boston Globe reports there's a Boston Marathon bombing suspect in custody and another on the loose in Watertown.
UPDATE: The officer has reportedly died.
Massachusetts Institute of Technology issued warning to students late Thursday night of shots being fired on campus.
According to the school's website, gunshots were reported in the vicinity of Building 32 in the Stata Center of the campus. School authorities have asked students to stay clear of the area while an investigation was underway.
The police officer reportedly suffered life-threatening injuries in the shooting, and was taken to an area hospital, a State Police spokesman told The Globe.
According to HuffPost's Michael McLaughlin, reporting from the ground, "About two dozen cops and detectives are clustered in an area south of Main St., a short distance from crime scene tape," with more police continuing to arrive by car.