Boston EMS said they responded at about midnight to the shooting near the Dorchester line.
Military and law enforcement personnel are urged to watch what they post on social media.
Boston Police Commissioner William Evans said officers approached a vehicle in Roxbury without guns drawn when Angelo West shot Officer John Moynihan at point blank range in the face.
An early morning Friday shooting left one woman injured.
A man was killed in a shooting near the Boston Waterfront on Sunday morning.
Two people were killed and a third was wounded in a shooting in Boston’s South End early Monday morning.
Two people have been arrested in connection with a fatal shooting inside a parking garage in Boston on Tuesday night.