Boston Marathon bombing suspect Dzhokhar Tsarnaev has been arrested following an extensive manhunt that ended in the Boston suburb of Watertown.

Chechen origin Dzhokhar Tsarnaev, who was already wounded from an earlier shootout, exchanged gunfire with police for an hour while holed up in the boat in the neighbourhood of Watertown.

The dramatic stand-off ended with the 19-year-old being given first aid on the lawn next to the boat before he was taken away in an ambulance at around 8.45pm local time.

Dzhokhar remains in “serious condition” at Beth Israel Deaconess hospital, said Boston police commissioner Ed Davis.

Swat teams surrounded the boat after a tip-off from a resident who noticed blood on it, Mr Davis said.

The man lifted the cover of the boat, saw the teenager covered in blood and alerted police.

A police helicopter then used infra-red equipment to confirm there was a human inside the boat.

Dzhokhar had been on the run since his 26-year-old brother and fellow suspect Tamerlan Tsarnaev  – known as suspect number one – was killed in a shoot-out with police in the early hours of Friday.

The brothers were believed to be behind Monday’s twin explosions at the Boston Marathon which left three people dead and around 180 wounded.

During their getaway attempt, they killed Massachusetts Institute of Technology policeman Sean Collier and severely wounded another officer, authorities said.

A crowd of residents cheered as Dzhokhar Tsarnaev – known as suspect number two – was taken into custody, and the celebrations continued into the night in the city’s streets.

Mayor Tom Menino said on Twitter: “We got him”.

Boston Police tweeted: “CAPTURED!!! The hunt is over. The search is done. The terror is over. And justice has won. Suspect in custody.”

The family of eight-year-old Martin Richard, who died in the bombings, released a statement praising police.

“Tonight, our family applauds the entire law enforcement community for a job well done, and trust that our justice system will now do its job,” the family said.

Martin’s mother also sustained brain injuries and his sister lost a leg in the blast.

US President Barack Obama told a news conference the suspect’s capture “closed an important chapter in this tragedy”.

But he said there were still many unanswered questions about the marathon bombings, including whether the two men had help from others.

As Dzhokhar was being captured, three people in New Bedford, Massachusetts, were also taken into custody for questioning over the blasts.

Lieutenant Robert Richard said two men and a woman were being questioned by the FBI “on the assumption there is an affiliation with suspect number two”.

Dzhokhar’s capture came at the end of a tumultuous all-day manhunt and house-to-house search by thousands of elite police officers.

As night fell, police announced that they were scaling back the hunt and they had so far come up empty-handed.

But shortly after that statement, a break came in Watertown when the homeowner – who had been indoors all day due to the manhunt – saw the blood on his boat.

The vessel had not been searched before because it was outside of the police perimeter set up during the search.

It has also been revealed that Tamerlan attracted the attention of US authorities two years ago.

The FBI said its agents interviewed him in 2011 at the request of a foreign government, but that the investigation found “no derogatory information”, according to an official.

The FBI declined to identify the country involved or the nature of the probe.

The brothers moved to the US a decade ago from a Russian region near Chechnya and had been living in Cambridge, Massachusetts, as legal permanent residents.

Their father, Anzor Tsarnaev, told reporters in Russia that he believed his sons had been framed and described the killing of Tamerlan as “cowardly”.

Maret Tsarnaev, the men’s aunt, said Tamerlan had recently become a devout Muslim who prayed five times a day.

Speaking to reporters at her home in Toronto, Canada, she also said the older brother was married and had a daughter in the US.

[adrotate banner=”46″]