Police officers told residents of Watertown near Boston to stay indoors as they looked for a second suspect for the April 15 marathon blasts in which three people were killed and about 180 injured.
The incident occurred during a massive manhunt which was launched in the wake of a shootout at Wharton and the killing of a police officer in the MIT campus and a frenetic car chase into Watertown on Thursday night.
Much of the town was sealed as the search operation for the second suspect was on, media reports said. The police reportedly created a 20-block perimeter in Watertown to catch hold of the suspect.
The authorities had earlier refused to comment on whether the manhunt had a link to Monday's blasts. However, the operation was launched just hours after the FBI released photos of the suspects they believed to have planted the explosives.
Another police officer was injured in the gunfight in the town, sources said.