UPDATE: Second suspect arrested .
UPDATE: Police identify  the victim as Rayshawn Lamont Few, 27.
As officers were responding to the scene, they saw a brown car fleeing the area at a "noteworthy" rate of speed, police say. The driver ignored blue lights and sirens until Donwood Terrace and Ridgeview Avenue , where the car stopped and three men got out and ran away, police say.
Officers managed to chase down Osmell Odena, 22, who was arrested on a charge of unlawful possession of a firearm and ammunition for the loaded gun they found between the car and where he was stopped, police say. The search for the other two suspects continues.
The victim, unidentified by police, is Boston's fourth murder victim  this year.