By the way, I wouldn’t characterize it as a “summary execution” in this case. I concede that it could be poor training. But not having been a cop, and showing up at a place where shooting is going on, and an unknown person is shooting into a house...no matter how you slice it, that is endangering your own life.
Handling a weapon is a massive responsibility, and the self-defense courses I have taken use case studies such as coming on a scene where someone is pointing a gun at someone else, and you can’t just shoot the person holding the weapon, that is true, as true for us as it is for cops. Heck, the person holding the weapon might have just disarmed someone who murdered someone else.
In this case, it all turned out bad.
My CCW class said if cops were responding to a “Shots fired” call, and found me holding a gun, they’d probably shoot me. Particularly if I held a rifle.