I’ll bet they were metal jacket target rounds.
Even a 185gr target round .45 will kill most if it’s a COM shot. I imagine he just flung it around firing all over.. Hitting bystanders is a good indication. I’m just surprised he hasn’t been charged with under 21 possessing and certainly possessing at school, which should’ve lifted the bail amount by a lot. Maybe they did though? Letting it slide? Strange.