BOSTON - The suspect being hunted in the Boston Marathon bombing was in a boat stored in Watertown, a law enforcement official said, and police in armored vehicles and tactical gear rushed into the neighborhood.
The burst of activity came after police announced that they were scaling back the hunt because they had come up empty-handed following an all-day search that sent thousands of SWAT team officers into the streets and paralyzed the metropolitan area.
A hail of gunfire was heard from the neighborhood, followed by a round of blasts about an hour later.
"We heard a series of shots, really staccato-like. Then 30 to 40 cops just rolled by and everything gets crazy," said Kevin Leblanc, of Reading, who had come to Watertown to see what was happening.
The official who said 19-year-old college student Dzhokhar Tsarnaev was in the boat had been briefed on the situation and spoke on condition of anonymity because he was not authorized to discuss it publicly.
Police say the 19-year-old suspect in the Boston Marathon bombings exchanged gunfire with law enforcement for an hour while holed up in a boat before being captured.
Boston Police Commissioner Ed Davis said Tsarnaev was hospitalized late Friday in serious condition.
Police have lifted the lockdown order and MBTA bus service has resumed. Authorities had earlier encouraged people in and around Boston to stay indoors for most of the day.
"We are asking public to remain vigilant," Gov. Patrick said at the conference.
The intensive manhunt for Dzhokhar Tsarnaev has been going on since early Friday and has included the seizure of at least two vehicles and a door-to-door search in Boston and the surrounding areas.
However, police said at the briefing that he later fled on foot, and there is no indication he currently has a vehicle.
Dzhokhar Tsarnaev's brother, 26-year-old Tamerlan Tsamenev, died overnight in a gunfight with police.
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Massachusetts State Police say the brothers spent Thursday evening in a Honda CRV that they used to carjack a Mercedes SUV.
Police said Friday morning at a Watertown news conference that one of the brothers stayed with the carjacking victim for a few minutes, then let him go.
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They say one brother drove away in the CRV, and the other one drove away in the Mercedes.
Police say one then ditched the CRV and reunited with his brother in the Mercedes. Authorities say both suspects were in the Mercedes later in the night when they killed an MIT police officer, injured a transit officer in a fire fight and threw explosive devices at police during their getaway attempt.
The MIT 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.
Hours earlier, police had released photos of the marathon bombing suspects and asked for the public's help finding them.
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The MIT shooting on the Cambridge campus Thursday night was followed by reports of gunfire and explosions in Watertown, about 10 miles west of Boston.
Authorities say the suspects threw explosives from the car as police followed it into Watertown. The suspects and police exchanged gunfire. Tamerlan Tsarnaev was killed and his brother escaped.
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."
The CRV and another vehicle - a green Honda Accord - believed to be linked to the suspects were found Friday and were being processed by police.
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!"
The FBI has removed a computer from the New Jersey home of his sister. Police in West New York say the woman is cooperating in the investigation, but they didn't immediately release her name.
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The sister said she doesn't know what got into her brothers. At the same time, she said she doesn't know if it's true that her brothers were responsible.