(CNN) — Two men suspected in the Boston Marathon bombings that killed three people may have terrorized the area a second time overnight. The latest developments:
— A man who police believe is a suspect in the Boston Marathon bombings was shot and killed by officers in an exchange of gunfire.
— A second suspect is at large in the Boston suburb of Watertown, where dozens of officers from local, state and federal law enforcement agencies have fanned out to track him down.
— Police are going door-to-door to look for him.
— The violence began late Thursday night when a Massachusetts Institute of Technology police officer was shot and killed when he responded to a disturbance on campus.
— Within an hour, police were called to respond to a carjacking, which led them on a chase of the two suspects through Watertown.
— The fleeing men allegedly used explosives against police as they were being chased.