Police announced via Twitter that Dzhokhar Tsarnaev was in custody. His brother, 26-year-old Tamerlan, was killed Friday in a furious attempt to escape police.
The brothers are suspects in Monday's marathon bombings, which killed three people and wounded more than 180 others. The men are also suspected of killing a Massachusetts Institute of Technology police officer in his vehicle late Thursday.
Authorities in Boston had suspended all mass transit and warned close to 1 million people in the entire city and some of its suburbs to stay indoors as the hunt for the remaining suspect went on.