Quincy police said a double shooting in a residential neighborhood early Wednesday was probably gang-related, and they are making headway in the inves­tigation, even though the victims and witnesses have been uncooperative.

Investigators are still piecing together what happened on ­Arlington Street in the ­Montclair neighborhood, where two Quincy men were shot while sitting in the back of a cab. The cab had pulled up to a house at 3:45 a.m. to let four passengers out, when a person came up to the cab and fired several shots through the door and window.