WATERTOWN, Mass.- Dzhokhar Tsarnaev, so-called "Suspect No. 2" in Monday's Boston Marathon bombings, was captured Friday night, hiding in a boat behind a house near Boston.

His brother, Tamerlan, was killed hours earlier in an attempt to escape police.

Dzhokhar, 19, was last reported in serious condition after a standoff with law enforcement that lasted almost an hour.

"We got him," Boston Mayor Tom Menino posted on his Twitter account shortly after Dzhokhar was taken into custody. The message was shared almost 20,000 times.

By late Friday, celebrations erupted in suburban Boston and beyond as news rapidly spread. In Boston, hundreds of people marched down Commonwealth Avenue, chanting "USA" and singing the Red Sox anthem "Sweet Caroline" as they headed toward Boston Common. Police blocked traffic along part of the street to allow for the impromptu parade.

Saturday morning, runners in Baton Rouge are planning a special 2.62-mile run through downtown for the victims of Monday's attack (a marathon is 26.2 miles). Nearly 100 runners from Louisiana were in Boston for the marathon; nearly two-dozen were from the Baton Rouge area. All escaped unharmed.

For more on this story, CLICK HERE for coverage from ABC News.
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