A police officer who was shot on the campus at the Massachusetts Institute of Technology has died from injuries.
Cambridge police and the Middlesex District Attorney's office said the officer was responding to a report of a disturbance when he was shot multiple times.
He later died in hospital, and his name was not immediately released.
State police spokesman Dave Procopio said the shooting took place about 10.30pm local time outside an MIT building.
He said the authorities are searching for a suspect or suspects, and no arrests have been made.
MIT police, Cambridge police and state police are involved in the investigation.
About 11,000 people attend the prestigious school outside Boston.
The campus website said police were sweeping the campus and urged people to stay indoors.