At 17 it was illegal for him to be in possession of that gun. It was also illegal for him to possess that gun in Mn. And it was illegal for him to be threatening, let alone shooting anyone, regardless of the circumstances. That's what's referred to as compounding a felony.
He's just another dumb kid (remember, he does not possess a prefrontal cortex at that age, and can't perform higher thinking tasks) who was improperly indoctrinated by his parents. Not the first kid I've/we've seen like that. But his errors will cost him a good portion, perhaps all of his freedom for the rest of his life, AND MORE IMPORTANTLY his parents will lose everything to the civil lawsuits that follow, and maybe even their freedom. Perhaps that is a small bit of justice for the mind fuc* they gave him.
Killing someone is almost never the best course of action, and that is something that most thinking adults will agree upon. (Some may want to read that sentence again carefully before you start flaming).
This is a very regrettable situation. 5 lives have been, or will be permanently changed for the worse, and for no good reason. A senseless act of violence by an unthinking minor in possession of a weapon that he should never had his hands on without adult supervision, and leaving 2 people dead.