I am not here to make excuses for anybody but an alternate scenario is this — the boy was bullied and wanted to get even, the parents were not aware of the full extent of the bullying (because parents tend to judge their kids by their own experiences, if you’re not being bullied as a parent in the community, why would your kid be bullied?) ... so there was little advance recognition of the potential for disaster, then this happened.
I draw those conclusions in part from my own experience, in that I was an immigrant (to Canada), I was bullied relentlessly from about age eight to fifteen, and my parents didn’t want to hear about it because they were fitting in and doing fine (but they weren’t mixing with the parents of my classmates). So I had to deal with it all myself. If anyone here thinks that is easy, you’re dead wrong. You are in a new country, not of your own choosing, you have no way out, you are in physical danger every day, and you are sick of the situation and want it to end.
It had effects on me that I worked out gradually through insight as I matured but in a culture like yours (where guns are available) I might have done that too, seriously, because I was that frustrated with the non-stop bullying.
So deal with that, it’s not abnormal to get royally pissed off at being bullied. If you want to have a culture of guns and bullying, expect more of this.
Am I not right? The truth shall set you free.