Boston police dealt with another night of violence last night, responding to a fatal shooting in Dorchester as well as another shooting in Roxbury, and becoming involved in a bizarre pursuit of a suspect that ended with his apprehension after he dove into the Mystic River, police said.

Boston Police Captain Jack Danilecki said the Dorchester victim, who was in his 20s but was not known to police, was shot several times at about 11:35 p.m. near the corner of Mascot Street and Mountain Avenue.

Danilecki said the victim was pronounced dead at Boston Medical Center. He said police had no leads on suspects as of early this morning.

Danilecki also said that another man in his 20s, who is known to police, was shot three times last night on Lenox Street in Roxbury.