I threw a shoe at a car on the highway, and in reaction to the shoe a man swerved off the road, went over the barrier, and hit a family walking on the sidewalk. Who killed the family? The shoe thrower or the man driving his truck home?
Sure cops are responsible to a point, but common, this goes deeper than just the face value.
The cops turn up to a swatting, in force, armed and armored. No matter what is happening at the gig, they are safe. They are certainly safe from a man in the open with a pistol. Even if one cop gets injured, the guy with the pistol is dead. The trouble is that if anyone fires a shot, and it's usually the cops, the civilian is also dead. The cops really have nothing much to fear and need to ask questions first before shooting. If they show up and shoot someone without asking any questions, it is murder.