Question the assumption made by the speaker that the event mentioned was done by gang members and suggest alternative possibilities such as anger, mental health issues or foolishness.
How do you know it was a gang? I didnt see that in the story? Couldnt it have been someone mad? Couldnt it have been someone with mental issues? Could it not have been an idiot? it may very well have been but assuming it was "gangbangers" is shortsighted IMHO.