Hmm, possibly. Can see a shotgun being effective at calming situations down, if years of bar fights in TVs have taught me anything.
As for wanting a lethal conclusion, eh, if the cops killed him justifiably or he offed himself, would be cheaper in long run and some people are worth tossing in a ditch (like anyone associated with dogfighting, for example). But him in a cell for his whole life is acceptable. Parents also may get charged, seems they got him the gun on Friday and I guess show no control over the weapon.
Can still beat them to death with it. Hitting someone once can open the flood gates of anger. So that's probably a risk.
I guess the best weapon to maintain order is to threaten them with Gnesa.