WATERTOWN, Massachusetts, (AFP) - Police said on Friday they had detained a teenaged suspect in the Boston marathon bombings after a showdown at a house in the suburbs.

"Suspect in custody. Officers sweeping the area. Stand by for further info," Boston police said on its Twitter account after 19-year-old Dzhokhar Tsarnaev was taken away to applause from people near the scene in Watertown.

"CAPTURED!!! The hunt is over. The search is done. The terror is over. And justice has won. Suspect in custody." Boston police tweeted.

Boston Mayor Thomas Menino tweeted a picture with the caption: "We got him."

Media reports said Tsarnaev had been hiding in a boat in the backyard of the house, after being wounded in an overnight shootout in which his brother Tamerlan, believed to have been the second bombing suspect, was fatally shot.

At one stage, a series of about 15 explosions erupted, which local television channels said could have been stun grenades. Gunfire had erupted in the district only minutes after police told a press conference they believed that Tsarnaev had escaped a mass dragnet thrown over Watertown.

The brothers, who are ethnic Chechens, are believed to have planted two bombs near the finish line of the Boston marathon on Monday - an attack in which three people were killed and about 180 wounded.