BOSTON The Boston suburb of Watertown turned into a virtual war zone overnight as hundreds of heavily armed police chased and confronted two suspects in the Boston Marathon bombing.
Residents watched out of their windows in terror as explosions and gunshots rocked the normally sleepy town.
Police killed one of the suspects in the shootout, while the other is the target of a house-to-house manhunt. A national security official identified the hunted man as Dzhokar A. Tsarnaev, 19, and said the dead suspect was his brother, Tamerlan Tsarnaev, 26.
Witnesses described a chaotic scene of fireballs, screeching police vehicles and law enforcement officers pointing assault weapons. Some witnesses said they saw men throwing grenades at the officers.
The fight ended up in Watertown after the two male suspects carjacked an SUV in Cambridge and led police on a high-speed chase. Witnesses said the suspects were firing out of their vehicle.
Nearby resident Kirk Kaloustian said an explosion woke him about 1 a.m., and he saw a car chase with police. "They were going about 80 miles per hour," Kaloustian told Reuters. "You could hear the engines roar."
Police immediately put out the word to residents to stay inside and lock their doors. Soon afterward, they also asked residents in several other nearby towns, including Cambridge, Newton and neighborhoods in Boston, to stay put as they continued their search.
By early Friday morning, Massachusetts Governor Deval Patrick said police had expanded the lockdown to the entire city of Boston. Police were asking people to stay inside, lock their doors and not admit anyone but properly identified police.
That applies to Cambridge, Watertown, Waltham, Newton, Belmont and now all of Boston, Patrick said.
Boston Mayor Thomas Menino urged citizens to be patient while police were "actively pursuing every lead in this active emergency event."
Around the region, mass transit, including subways, buses, commuter rail and Amtrak trains, was immediately shut down, leaving the city of Boston a virtual ghost town as people were unable to get to work.
Pictures from Watertown showed columns of police SWAT team officers in black uniforms with helmets taking up positions around the neighborhood.
Other officers patrolled with dogs, while still others rolled through the streets in armored vehicles.
Witnesses said police were shouting orders at bystanders to turn off their cellphones for fear that the devices might accidentally detonate more explosives.
Police have been working day and night since Monday to try to find out who set off two bombs at the Boston Marathon, killing three and injuring more than 170. This manhunt began just hours after the FBI released photos and videos on Thursday of two suspects and appealed to the public for help in finding the two young men seen in the images.
(Reporting by Svea Herbst-Bayliss and Stephanie Simon; Additional reporting by Tim McLaughlin; Editing by Lisa Von Ahn)