The 19-year-old suspect wanted in connection with the Boston Marathon bombings which killed three people and wounded more than 180 others is in custody after an extensive manhunt involving thousands of law enforcement officials, police say.

Police announced via Twitter that Dzhokhar Tsarnaev was in custody. They later wrote, "CAPTURED!!! The hunt is over. The search is done. The terror is over. And justice has won. Suspect in custody."

Dzhokhar's brother, 26-year-old Tamerlan, who was also a suspect in the bombing, died early Friday morning after a gunfight and car chase during which he and his younger brother hurled explosives at police from a stolen car, authorities said. During the getaway attempt, the brothers are suspected of killing an MIT policeman and severely wounded another officer, authorities said.

After a long day of door-to-door searches in the Boston suburb of Watertown, gunfire erupted Friday night amid the manhunt for the surviving suspect. Police in armoured vehicles and tactical gear rushed into the suburb, where the suspect had been hiding in a boat stored behind a house.

Boston Police Commissioner Ed Davis told reporters that they were notified about the possible presence of the suspect by a man who stepped outside after staying inside all day. The man walked outside and saw blood on the boat. He then opened the tarp and saw a man inside covered in blood, Davis said.

"He retreated and called us," Davis told reporters at a news conference after the announcement that the suspect was in custody. He said police set up a perimeter around the boat, and "over the course of the next hour or so, we exchanged gunfire with the suspect who was inside the boat."

Davis said he didn't know if the suspect had been wounded in the gunfire exchange or the night earlier.

Davis said the FBI hostage rescue team eventually entered the area and removed the suspect from the boat. He said the rescue team had tried to talk him out but that he was not communicative.

Davis said the suspect is in "serious condition" in hospital.

Dzokhar Tsarnaev, the 19-year-old suspect wanted in connection with the Boston Marathon bombings, on the ground after being arrested in a Boston suburb. (Courtesy of CBS News)

The crowd that gathered near the scene let out a cheer when spectators saw officers clapping after he was detained.

'We got him'

Boston Mayor Tom Menino tweeted, "We got him."

Davis said police didn't know exactly where the suspect went after fleeing police following the overnight exchange of gunfire.

"We found some blood in a place where he might have spent some time in the middle of the night," Davis told CNN in an interview. "At some point he made his way about a half mile, maybe a little farther, to the location of the boat."

The boat was "just outside" the perimeter of the search, Davis said, so teams didn't look in that area during their initial probe of the area .

"He holed up there until he was discovered by the boat owner."

Dzhokhar Tsarnaev, left, a suspect in the Boston Marathon bombings, was captured Friday night. His brother, Tamerlan Tsarnaev, also a suspect in the bombing, died after a shootout with police eary Friday morning. (Robin Young/The Lowell Sun/AP)

U.S President Barack Obama thanked law enforcement officials involved in the investigation, but noted there are still unanswered questions.

"Among them, why did young men who grew up and studied here as part of our communities and our country resort to such violence? How did they plan and carry out these attacks, and did they receive any help," he said, adding that the victims deserve answers.

In an earlier news conference, State Police Col. Timothy Alben said that he believed Dzhokhar Tsarnaev was still in Massachusetts because of his ties to the area. But authorities lifted the stay-indoors warning for people in the Boston area, and the transit system started running again by evening.

Lock down lifted

Massachusetts Gov. Deval Patrick lifted the lockdown that had been in place for Boston and some surrounding areas Friday evening around 6 p.m., after hours of door-to-door searching.

During the lockdown, people were urged to stay in their homes and lock their doors. Businesses were quiet, universities and colleges were closed and transit was shut down.

The FBI said Dzhokar Tsarnaev, suspect in the Boston Marathon bombing, is now in custody. His brother, Tamerlan died after a firefight. (FBI)

Patrick said Friday evening that officials felt justified in ordering the lockdown.

"There was a firefight out here last night, some 200 rounds and explosives," the governor said during a news conference held in Watertown, the Boston suburb where the suspect was eventually captured.

"So we were very justified, I believe based on what we understood about the investigation, in taking what we knew was a big step in asking people to stay indoors where we went house-to-house here, and in other communities close by," Patrick said.

During a news conference, law enforcement officials thanked people for their patience and paid respect to the victims.

"In our time of rejoicing, let us not forget the families of Martin Richard, Lingzi Lu, Krystle Campbell and Officer Sean Collier," Boston Police said on Twitter.

Richard, Lu and Campbell were killed when twin blasts ripped through an area near the finish line of the famed marathon on Monday.

Collier, a MIT police officer, died last night. Authorities say the Tsarnaev brothers gunned down the 26-year-old officer as he sat in his cruiser at 10:20 p.m. Collier had not drawn his weapon, officials say.