With a bomb strapped to his chest, one of the Boston Marathon suspects was killed early Friday after he and his accomplice brother robbed a 7-Eleven, shot a police officer to death, carjacked an SUV and hurled explosives in an extraordinary firefight with law enforcement, as reported by NBC News.

The second suspect - the one in the white hat in photos released by the FBI - was on the loose, news reports said.

Massachusetts Governor Deval Patrick ordered the entire city of Boston and some suburbs to stay inside during what he called a "massive manhunt," and police began a house-to-house search. Boston shut down its buses and subway system.

The suspects are brothers of Chechen origin with the last name Tsarnaev, law enforcement officials told NBC News.

The suspect at large, Dzhokhar Tsarnaev, is 19, was born in Kyrgyzstan and has a Massachusetts driver's license, they said.

The dead suspect was identified as Tamerlan Tsarnaev, 26, born in Russia.

Tamerlan Tsarnaev was run over by a vehicle during the firefight, law enforcement officials told NBC News. Law enforcement officials also told NBC News that the brothers entered the United States with family in 2002 or 2003, and that Tamerlan Tsarnaev became a legal permanent resident in 2007.

The chaotic sequence of events started six hours after the FBI triggered a nationwide manhunt by releasing photos of the suspects, believed responsible for detonating two bombs at the marathon finish line Monday, killing three people and injuring 176.

 "There is a terrorist on the loose," a law enforcement officer said at a press conference before dawn.