because someone said they're armed

Except that's not what happened. The "swatter" gave the address as his own, and pretended to be a resident of the house who had shot his father and doused the house in gasoline. You literally only read the title and feel like you know everything already. They hadn't been told "there's an armed man in that house" they had been told "I'm in this house, I shot my father, I doused the house in gasoline, I'm holding people hostage, I want to kill them". They are then faced with a man opening the door because he thought something was going on outside and very, very unfortunately being shot. They didn't call him out of the house, he opened the front door by himself and tried to see what was going on. You can only imagine or guess what the officers were thinking about why this guy who was going to set the house on fire and kill everyone inside had just left the house. Of course it's a fucking tragedy but you can't judge everything as black and white. Should the guy who shot him and the entire team be thoroughly investigated and punished accordingly? Yes, of course. But if you think it's the police who are the root of the issue here then you might want to remind yourself that a fucking grown man called up and instigated the entire thing as a joke. Where do you think the real malice is here?