Police in Cambridge, Massachusetts, are urging students of the Massachusetts Institute of Technology to stay indoors as they hunt for a gunman who fatally shot a police officer late Thursday evening.
Campus police said the police officer was shot multiple times while responding to a disturbance on campus and later died of his wounds in the hospital.
A large area of campus has been cordoned off as security forces fan out to look for the suspect.
Meanwhile, in nearby Watertown, police have detained at least one person in a scene featuring blaring sirens and multiple police vehicles. It is unclear whether the suspect were detained for the campus shooting or in connection with Monday's Boston Marathon bombing, which took place just across the Charles River.