[Updated 1:49 a.m. ET]
At least one person was arrested in Watertown, Massachusetts early Friday morning, stripped naked before being taken in custody, CNN photojournalist Gabe Ramirez observed. It is unclear if this arrest was related to the shooting at Massachusetts Institute of Technology campus or any other incident in Boston the area.
[Updated 1:23 a.m. ET]
Dozens of police have rushed to an area of Watertown, Massachusetts, just over two miles from Cambridge, said CNN's Drew Griffin, who is near the scene. A "very large event has taken place," Griffin said. There were reports that explosives were involved.
[Posted at 12:45 a.m. ET]
A university police officer has died after being shot on the Massachusetts Institute of Technology campus in Cambridge late Thursday, state police spokesman Lt. Mark Riley said. The MIT officer was responding to a disturbance when he was shot, according to the state district attorney's office. He sustained "multiple gunshot wounds."
State police and the FBI were called in after the shooting and found the campus policeman near Building 32 on MIT's campus. He was taken to Massachusetts General Hospital, where he was pronounced dead, the district attorney's office said. Dozens of officers surrounded and cordoned off the building, known as the Stata Center, which houses computer science laboratories as well as the department of linguistics and philosophy, according to MIT's website.