This is a developing story and will be updated as soon as new information becomes available. Further below, you'll find AFP's live coverage. Reload this page for updates.
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Update from The Raw Story, 10:12 p.m. EST: Boston Police Commissioner Ed Davis said the living suspect, Dzhokhar Tsarnaev, was in serious condition at a local hospital. He said authorities located Tsarnaev after being alerted by a Watertown, Massachusetts resident who saw him "covered in blood" in a boat in his backyard.
Davis said the suspect exchanged gunfire with police, then became uncommunicative, before a hostage rescue team took him into custody.
U.S. attorney Carmen Ortiz said the government "had an opportunity" to invoke a public safety exemption allowing for limited interrogation of the suspect before he is read his Miranda rights.
In a separate statement, President Barack Obama said he had authorized the Federal Bureau of Investigation to use all its resources as the investigation continued. He also said the needs of the residents of West, Texas -- site of a massive explosion at a fertilizer plant Wednesday night -- would not be forgotten.
"All in all, this has been a tough week," Obama said. "But we have seen the character of our contry once more."
Update from The Raw Story, 9:10 p.m.: The Huffington Post reported that the family of Katherine Miller, the widow of 26-year-old suspect Tamerlan Tsarnaev, released a statement Friday night.
"Our daughter has lost her husband today, the father of her child," the family said in its statement. "We cannot begin to comprehend how this horrible tragedy occurred. In the aftermath of the Patriot's Day horror, we know that we never really knew Tamerlane [sic] Tsarnaev."
Tamerlan Tsarnaev was killed in a firefight with authorities Thursday night.
Update from The Raw Story, 8:45 p.m.: The Boston Globe has reported that 19-year-old suspect Dzhokhar Tsarnaev has been taken in custody after being found under a tarp on a boat in a residential backyard. WBZ-TV and The Globe said there was a "wave of applause" from the scene of the stand-off after Tsarnaev was arrested. WBZ also reported that the suspect is being taken to a hospital.
Update from The Raw Story, 8:24 p.m. EST: In a statement released Friday night, Petr Gandalovič, Czechoslovakian ambassador to the U.S., clarified what he called a "social media misunderstanding" regarding the investigation.
"The Czech Republic and Chechnya are two very different entities - the Czech Republic is a Central European country; Chechnya is a part of the Russian Federation," Gandalovič said. "As the President of the Czech Republic Miloš Zeman noted in his message to President Obama, the Czech Republic is an active and reliable partner of the United States in the fight against terrorism."
Update from The Raw Story, 7:50 p.m. EST: The Boston Globe and WBZ-TV have reported that police have surrounded 19-year-old suspect Dzhokhar Tsarnaev, who is on a boat in a backyard in Watertown, Massachusetts.
Update from The Raw Story, 7:18 p.m.: Boston Police have reinstated their request for Watertown, Massachusetts, residents to stay indoors.
Update from The Raw Story, 6:30 p.m. EST: Massachusetts State Police Superintendent Col. Timothy Alben confirmed at a press conference that 19-year-old suspect Dzhokhar Tsarnaev had not been apprehended.
"I don't have any direct knowledge that he's in the Boston area, but I don't think that he'd get much further," said Alben, who added that the suspect escaped on foot. "His ties seem to be here."
Alben also confirmed that neither the living suspect nor his brother, 26-year-old Tamerlan Tsarnaev, were involved in a robbery at a 7-Eleven store in Watertown, Massachusetts that previous reports had linked to their pursuit.
Also, Gov. Deval Patrick (D) said the order for Watertown residents to stay in their homes had been lifted, and that Massachusetts Bay Transportation Authority services had been re-opened.
0146 GMT: The Boston Globe reports that the suspect is enroute to Beth Israel Deaconess Medical Center, not Mt. Auburn as previously reported. His brother, Tamerlan, was pronounced dead there this morning. 0144 GMT: Boston Mayor Tom Menino applauded emergency workers and said, "the people of the greater…