Black Hawk helicopters and heavily armed police descended on a Boston suburb Friday in a massive search for an ethnic Chechen suspected in the Boston Marathon bombings, hours after his brother was killed by police in a late-night shootout.
The normally traffic-clogged streets of Boston were empty as the city went into virtual lockdown after a bloody night of shooting and explosions. Public transport was suspended, air space restricted and famous universities, including Harvard and MIT, closed after police ordered residents to remain at home.
Officials identified the hunted man as Dzhokhar Tsarnaev, 19, and the dead suspect as his brother, Tamerlan Tsarnaev, 26, who was killed Thursday night in the working class suburb of Watertown.
Details emerged on Friday about the brothers, including their origins in the predominantly Muslim regions of Russia's Caucasus, which have experienced two decades of violence since the fall of the Soviet Union.
The fugitive described himself on a social network as a minority from a region that includes Chechnya, Dagestan and Ingushetia.
A man who said he was their uncle said the brothers came to the United States in the early 2000s and settled in the Cambridge, Massachusetts, area.
"I say what I think what's behind it - being losers," Ruslan Tsarni told reporters in suburban Washington. "Not being able to settle themselves and thereby hating everyone who did."
Tsarni said he had not spoken to the brothers since 2009.
He said Monday's bombings on the finish line of the world-famous Boston Marathon that killed three people and injured 176 "put a shame on our family. It put a shame on the entire Chechen ethnicity."
The bombing, described by President Barack Obama as "an act of terrorism," was the worst such attack on U.S. soil since the plane hijackings of Sept. 11, 2001.
The FBI said the twin blasts were caused by bombs in pressure cookers and carried in backpacks that were left near the marathon finish line as thousands of spectators gathered.
Authorities cordoned off a section of the suburb of Watertown and told residents not to leave their homes or answer the door as officers in combat gear scoured a 20-block area for the missing man, who was described as armed and dangerous.
The manhunt has covered 60 percent to 70 percent of the search area, Massachusetts State Police Colonel Timothy Alben said Friday afternoon. "We are progressing through this neighborhood, going door-to-door, street-to-street," he said.
Two Black Hawk helicopters circled the area. Amtrak said it was suspending train service between Boston and New York indefinitely and the Boston Red Sox postponed Friday night's baseball game at historic Fenway Park.
The events elicited a response from Moscow condemning terrorism and from the Russian-installed leader of Chechnya, who criticized police in Boston for killing an ethnic Chechen and blamed the violence on his upbringing in the United States.
"They grew up and studied in the United States and their attitudes and beliefs were formed there," Ramzan Kadyrov said in comments posted online. "Any attempt to make a connection between Chechnya and the Tsarnaevs is in vain."
The brothers had been in the United States for several years and were believed to be legal immigrants, according to U.S. government sources. Neither had been known as a potential security threat, a law enforcement official said on Friday.
A Russian language social networking site bearing Dzhokhar Tsarnaev's name paid tribute to Islamic websites and to those calling for Chechen independence. The author identified himself as a 2011 graduate of Cambridge Rindge and Latin School, a public school in Cambridge, Massachusetts.
He said he went to primary school in Makhachkala, capital of Dagestan, a province in Russia that borders on Chechnya, and listed his languages as English, Russian and Chechen.
His "World view" was listed as "Islam" and his "Personal priority" as "career and money."
He posted links to videos of fighters in Syria's civil war and to Islamic web pages with titles such as "Salamworld, my religion is Islam" and "There is no God but Allah, let that ring out in our hearts."
He also had links to pages calling for independence for Chechnya, a region of Russia that lost its bid for independence after two wars in the 1990s.
Video posted on NJ.com showed a woman, Alina Tsarnaeva, who described herself as a sister of the suspects.
"I'm not OK, just like anyone else is not OK," she told reporters from behind the closed door of an apartment in West New York, New Jersey.
She said the older brother "was a great person. He was a kind and loving man. To piss life away, just like he pissed others' life away ... "
She said of the younger brother, "He's a child."
In Watertown, the lockdown cleared the streets for police, who raced from one site to the next. The events stunned the former mill town, which has a large Russian-speaking community.
During the night, a university police officer was killed, a transit police officer was wounded, and the suspects carjacked a vehicle before leading police on a chase that led to Tamerlan Tsarnaev being shot dead.
"During the exchange of the gunfire, we believe that one of the suspects was struck and ultimately taken into custody," Alben said.
The suspect died of multiple injuries including gunshot wounds and trauma, said Dr. Richard Wolfe, chief of emergency medicine at Beth Israel Deaconess Medical Center.
The older brother was seen wearing a dark cap and sunglasses in surveillance images released by the FBI on Thursday. The younger Tsarnaev was shown wearing a white cap in the pictures, taken shortly before Monday's explosions.
"We believe this to be a terrorist," said Boston Police Commissioner Ed Davis. "We believe this to be a man who has come here to kill people. We need to get him in custody."
Additional reporting by Mark Hosenball, Alex Dobuzinskis, David Bailey, Peter Graff, Stephanie Simon, Svea Herbst-Bayliss, Aaron Pressman, Daniel Lovering and Ben Berkowitz; Writing by Daniel Trotta and Grant McCool; Editing by Doina Chiacu