Sadly stuff like this only going to become more common because our society doesn't detain people who are mentally ill until they are possibly habilitated, and worse our society essentially permits mentally ill, deranged people to walk the streets and commit heinous acts of violence and would be victims cannot defend themselves with weapons and a proportionate response without fear of the law, even when being viciously attacked.
The Police: "Our response times are too slow? You are your own first responder! Hold out until we get there!"
Also The Police: "You were being attacked and you pulled out your firearm and shot him? You shot him three times, once in the back. He turned around and tried to flee after the first few shots and you kept shooting out of fear for your life? Can you prove that because there are no cameras in the area?"
ALSO
The Police: "You should shot and killed your neighbor through your door? She was coming to hurt you? *Sees that the dead woman is a minority and that the shooter is white* "Guess the story checks out. Sorry it had to come to this. We'll take it from here, have a good day ma'am."