Since the deputies did not identify themselves they should be found at fault and charged with murder. They were worried about their safety and no one elses.
....This is almost ignore worthy...
They were chasing someone who attempted to kill someone.
Said person then parks his bike outside of this guy's house.
The police (trying to not let the world know they were there for obvious reasons) then knocked on the door and this guy decided to open the door with a gun pointed at the cops. I would have fragged him too.
You're trained that when someone points a weapon at you, you take them down. Especially if your chasing a potential murder suspect.
Hell my neighbors next door have a hole in their house from a shotgun blast that was fired by a police officer. Why? Because my neighbor is a moron and was walking around outside with his shotgun talking about killing everyone. He's lucky they didn't frag him then and there.