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.