Saw the article. The shooter was a crazy older guy & he apparently murdered his sister, too! Here's what apparently went down.....
This is a suicidal psychopath who likes to kill for funzies.
He lived with his sister, whom he apparently couldn't stand.
He killed said sister, then set the house on fire, the fire wasn't just a trap, it apparently was to destroy evidence, including the body, hence the shooting of firefighters.
He then killed himself, the police found the sister's remains later.
He left a suicide note that said that he hated the world and that killing was what he did best.