Manhunt Under Way, Boston Suburbs Shut Down

Boston Police locked down some neighborhoods in Boston and its western suburbs as they searched for the remaining suspect in the Marathon bombings, known as the man in the white hat from marathon surveillance footage.

Authorities urged residents in Watertown, Newton, Waltham, Belmont, Cambridge and the Allston-Brighton neighborhoods of Boston to stay indoors. All mass transit was shut down and businesses were asked not to open Friday. People waiting at bus and subway stops were told to go home.

All schools in the Boston area are closed, according to CNN.

"We believe this to be a terrorist," said Boston Police Commissioner Ed Davis of the suspect on the loose. "We believe this to be a man who's come here to kill people. We need to get him in custody."

All modes of public transportation were shut down, including buses, subways, trolleys, commuter rail and boats, said Joe Pesaturo, spokesman for the Massachusetts Bay Transportation Authority.

The Middlesex district attorney said the two men are suspected of killing a Massachusetts Institute of Technology police officer on campus in Cambridge late Thursday, then stealing a car at gunpoint and later releasing its driver unharmed.

Hours earlier, police had released photos of the marathon bombing suspects and asked for the public's help finding them. A new photo of the suspect on the loose was released later showing him in a grey hoodie sweatshirt. It was taken at a 7-Eleven in Cambridge, just across the Charles River from Boston.

The first images were released hours after President Barack Obama and first lady Michelle Obama attended an interfaith service at a Roman Catholic cathedral in Boston to remember the bombing victims.

Authorities say the suspects threw explosives from the car as police followed it into Watertown. The suspects and police exchanged gunfire, and one of the suspects was critically injured and later died at a hospital while the other escaped.

The FBI said it was working with local authorities to determine what happened.

Doctors at Beth Israel Deaconess Medical Center in Boston where a suspect in the marathon bombings was taken and later died said they treated a man with a possible blast injury and multiple gunshot wounds. They wouldn't say if the patient they treated, who came in with police, was the suspect in the black hat from marathon surveillance footage.