Images taken from a video released by the FBI
Police on Friday said that one of two suspects in the shooting of a Massachusetts Institute of Technology (MIT) police officer is dead and a massive manhunt is underway for another, who is believed to be tied to the Boston Marathon bombing.
Shortly after the MIT officer was shot dead on Thursday night, police got a report of a hijacking in Cambridge, just outside Boston. One of the two suspects in that officer's shooting was killed. Police said of the at-large suspect: "We believe this to be a terrorist, we this to a man who has come here to kill people."
The Federal Bureau of Investigation (FBI) said it was working with local authorities to determine what happened.
The MIT shooting on the Cambridge campus on Thursday night was followed by reports of violence in nearby Watertown, west of Boston.
State police spokesperson David Procopio had said there was a "strong possibility" the incidents are related.
The MIT officer had been responding to report of a disturbance on 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.
'I heard a loud boom'
In Watertown, witnesses reported hearing multiple gunshots and explosions at about 1am (5am GMT) on Friday. Dozens of police officers and FBI agents were in the neighbourhood and a helicopter circled overhead.
State police spokesperson David Procopio said, "The incident in Watertown did involve what we believe to be explosive devices possibly, potentially, being used against the police officers."
Boston cab driver Imran Saif said he was standing on a street corner at a police barricade across from a diner when he heard an explosion.
"I heard a loud boom and then a rapid succession of pop, pop, pop," he said. "It sounded like automatic weapons. And then I heard the second explosion."
He said he could smell something burning and advanced to check it out but area residents at their windows yelled at him, "Hey, it's gunfire! Don't go that way!"
MIT said right after the 10:30pm (2.3am GMT) shooting that police were sweeping the campus in Cambridge and urged people to remain indoors. They urged people 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.
– Reuters, AFP