WATERTOWN, Mass. (AP) - 3:01AM UPDATE:
A tense night of police activity just days after the Boston Marathon bombings has caused police to converge on a neighborhood outside Boston where they say there were explosives.
The chaos in Watertown, about 10 miles west of Boston, occurred just hours after a Massachusetts Institute of Technology police officer was shot and killed on campus. It was unclear if the outbursts of violence were related.
No arrests had been made in the officer's fatal shooting, and a manhunt was on for the shooter.
The officer had been responding to report of a disturbance Thursday night when he was shot multiple times, according to a statement from the Middlesex district attorney's office and Cambridge police. It said there were no other victims.
Meanwhile, in Watertown, witnesses reported hearing multiple gunshots and explosions at about 1 a.m. Friday. Dozens of police officers and FBI agents were in the neighborhood and a helicopter circled overhead.
State police spokesman David Procopio said, "The incident in Watertown did involve what we believe to be explosive devices possibly, potentially, being used against the police officers."
MIT said right after the 10:30 p.m. shooting that police were sweeping the campus in Cambridge and urged people to remain indoors. They urged people urged to stay away from the Stata Building, a mixed-use building with faculty offices, classrooms and a common area.
Hours later, MIT, which has about 11,000 students, said the campus was clear but the shooter was still on the loose.
Police have converged on a neighborhood outside Boston where there were reports of explosives being detonated and police are telling reporters to turn off their cell phones.
Dozens of officers and National Guard members are in Watertown, where television outlets report that gunfire and explosions have been heard. A helicopter is circling overhead.
Authorities early Friday were calling for somebody to get on the ground and put their hands up and a loud thud was heard after someone shouted "fire in the hole."
Reporters are being told to move away from the scene. A police officer told a reporter: "If you want to live, turn off your cell phone."
Earlier Thursday night a campus police officer was shot and killed at MIT and authorities were searching for the person responsible.
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