WATERTOWN, Mass. (AP) — A Massachusetts college student wanted in the Boston Marathon bombing was captured hiding out in a boat parked in a backyard Friday and his older brother lay dead in a furious 24-hour drama that transfixed the nation and paralyzed the Boston area with fear.

The bloody endgame came four days after the bombing and just a day after the FBI released surveillance-camera images of two young men suspected of planting the pressure-cooker explosives that ripped through the crowd at the marathon finish line, killing three people and wounding more than 180.

The two men were identified by authorities and relatives as ethnic Chechens from southern Russia who had been in the U.S. for about a decade and were believed to be living in Cambridge, Mass. But investigators gave no details on the motive for the bombing.

Early Friday morning, 26-year-old Tamerlan Tsarnaev was killed in a ferocious gun battle and car chase during which he and his younger brother hurled explosives at police from a stolen car, authorities said. The younger brother managed to escape.

During the getaway attempt, the brothers killed an MIT policeman and severely wounded another officer, authorities said.

After a tense tumultuous all-day manhunt and house-to-house search by thousands of SWAT team officers with rifles and armored vehicles, Dzhokhar Tsarnaev, 19, was cornered in a homeowner's yard, where he exchanged gunfire with police while holed up in a boat, authorities said.

He was taken away on a stretcher and was hospitalized in serious condition with unspecified injuries, police said.

Just before 9 p.m., Boston 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."

A cheer went up from a crowd of bystanders in Watertown.

"Everyone wants him alive," said Kathleen Paolillo, a teacher.

Boston Mayor Tom Menino tweeted "We got him," along with a photo of himself talking to the police commissioner.

Police said three other people were taken into custody for questioning at an off-campus housing complex at the University of the Massachusetts at Dartmouth where the younger man may have lived.

Up until the younger man's capture, it was looking like a grim day for police. As night fell, they announced that they were scaling back the hunt because they had come up empty-handed.

But then a break came in a Watertown neighborhood when a homeowner saw blood on his boat, pulled back the tarp and saw the bloody suspect inside, police said.

Chechnya has been the scene of two wars between Russian forces and separatists since 1994, in which tens of thousands were killed in heavy Russian bombing. That spawned an Islamic insurgency that has carried out deadly bombings in Russia and the region, although not in the West.

The older brother had strong political views about the United States, said Albrecht Ammon, 18, a downstairs-apartment neighbor in Cambridge. Ammon quoted Tsarnaev as saying that the U.S. uses the Bible as "an excuse for invading other countries."

Also, the FBI interviewed the older brother at the request of a foreign government in 2011, and nothing derogatory was found, according to a federal law enforcement official who was not authorized to discuss the case publicly and spoke on condition of anonymity.

The official did not identify the foreign country or say why it made the request.

The search for the younger brother all but paralyzed the Boston area for much of the day. Officials shut down all mass transit, including Amtrak trains to New York, advised businesses not to open, and warned close to 1 million people in the entire city and some of its suburbs to stay inside and unlock their doors only for uniformed police.

"We believe this man to be a terrorist," Boston Police Commissioner Ed Davis said. "We believe this to be a man who's come here to kill people."

Around midday, the suspects' uncle Ruslan Tsarni of Montgomery Village, Md., pleaded on television: "Dzhokhar, if you are alive, turn yourself in and ask for forgiveness."

Authorities said the man dubbed Suspect No. 1 — the one in sunglasses and a dark baseball cap in the surveillance-camera pictures — was Tamerlan Tsarnaev, while Suspect No. 2, the one in a white baseball cap worn backward, was his younger brother.

Exactly how the long night of crime began was unclear. But police said the brothers carjacked a man in a Mercedes-Benz in Cambridge, just across the Charles River from Boston, then released him unharmed at a gas station.

They also shot to death a Massachusetts Institute of Technology police officer, 26-year-old Sean Collier, while he was responding to a report of a disturbance, investigators said.

The search for the Mercedes led to a chase that ended in Watertown, where authorities said the suspects threw explosive devices from the car and exchanged gunfire with police. A transit police officer, 33-year-old Richard Donohue, was shot and critically wounded, authorities said.

Some 200 spent shells were found afterward.

Dzhokhar Tsarnaev somehow slipped away. He ran over his already wounded brother as he fled, according to two law enforcement officials who spoke on condition of anonymity because they were not authorized to discuss the investigation. At some point, he abandoned his car and ran away.

Tamerlan Tsarnaev died at a Boston hospital after suffering what doctors said were multiple gunshot wounds and a possible blast injury.

The brothers had built an arsenal of pipe bombs, grenades and improvised explosive devices and used some of the weapons in trying to make their getaway, said Rep. Dutch Ruppersberger, D-Md., a member of the House Intelligence Committee.

Watertown resident Kayla Dipaolo said she was woken up overnight by gunfire and a large explosion that sounded "like it was right next to my head ... and shook the whole house." She said she was looking at the front door when a bullet came through the side paneling. SWAT team officers were running all over her yard, she said.

"It was very scary," she said. "There are two bullet holes in the side of my house, and by the front door there is another."

Tamerlan Tsarnaev had studied accounting as a part-time student at Bunker Hill Community College in Boston for three semesters from 2006 to 2008, the school said.

Dzhokhar Tsarnaev was registered as a student at the University of Massachusetts Dartmouth. Students said he was on campus this week after the Boston Marathon bombing. The campus closed down Friday along with colleges around the Boston area.

The men's father, Anzor Tsarnaev, said in a telephone interview with AP from the Russian city of Makhachkala that his younger son, Dzhokhar, is "a true angel." He said his son was studying medicine.

"He is such an intelligent boy," the father said. "We expected him to come on holidays here."

The city of Cambridge announced two years ago that it had awarded a $2,500 scholarship to him. At the time, he was a senior at Cambridge Rindge & Latin School, a highly regarded public school whose alumni include Matt Damon, Ben Affleck and NBA Hall of Famer Patrick Ewing.

Tsarni, the men's uncle, said the brothers traveled here together from Russia. He called his nephews "losers" and said they had struggled to settle in the U.S. and ended up "thereby just hating everyone."