can you tell me why it is important to specify up front whether it was all a single shooting incident?
Because multiple/many instances of gang violence, domestic violence, robbery, et al. in a highly populated area are separate issues than someone purposefully shooting into a crowded concert from a nearby hotel room window or else running down scores of people on the sidewalk with a truck.
The circumstances involved with, and the societal impact of, one person shooting sixty people versus sixty people shooting one person each, is significant enough to be relevant to the story. Omitting such information skews the response people will give, which is to say it leads people to become misinformed based on (understandably) inaccurate assumptions.