Ethical, Moral, or legal?
Maybe some more facts will come out, maybe one of the kids brandished a gun, who knows. Regardless of the whole story, there are a few lessons (and we've all seen these same lessons before) to remember here.
First - if you think there's a threat of GBH outside, you don't go outside! Let alone take a weapon with you. Arm yourself, stay inside, call 9-1-1. Stay on the phone, or have your spouse stay on the phone with them till the mounties arrive. Stay in your safe spot. Having a gun, let alone a CCW permit ,doesn't make you a vigilante and you imperil all our rights when reactionary people read stories about trigger-happy citizens. You just don't use deadly force for a property crime, especially something as innocent and prankish as TPing a house.
Second - If you don't think there's a threat of GBH, you don't pull a gun. Ever. Period. Still call the cops if they're vandalizing your property - if they're caught in the act, they'll probably have to clean it up, at the least, when the judge gets the case. If one of them has a gun, tell the cops and let them - the pros, by the way - do their jobs. But a TP job by youngsters? Just step outside and shout at them - they'll run like the dickens almost certainly. Of course then you're stuck with the cleanup.
Third - THINK! BEFORE! YOU! ACT! Most adults are capable of foreseeing consequences from their actions. This situation didn't call for violence at all, let alone gunshots. Right or wrong, guilty or justified, the entire thing was almost certainly avoidable. Even if the shooting isn't prosecuted, nobody needed to get shot at all.
and for those of you who condone this shooting, i strongly suggest you re-think your own reaction strategies. It's one thing to shoot a burglar in your home; it's the same thing to shoot a would-be mugger where weapons or violence is either explicit or easily implied; this isn't any of those things. If your plan includes reacting with deadly force to such innocent and non-threatening situations, you are courting disaster and needlessly endangering yourself and others. Consider reviewing the CCW and deadly force laws in your area. You should know them by heart anyway.