Why shoot everyone?

Such a stupid solution. He should've either done like his father told him, i.e. stand up to the *beep* herd leader, or if he's not man enough for that, he should simply tell everything to parents and teachers, the bullies would get kicked out of school, end of story. I mean what's the worst that could happen? Maybe he'd get beat up pretty bad, but that would just confirm his story and the violent bullies would get expelled right away. Poor Kaspar ruining his life for a pussy like Josep.