Did the guy go beyond reasonable self-defense? Yeah, most likely.
Do I feel sorry for the kids who got killed? No. They shouldn't have been breaking into the guy's house in the first place.
Yes, this guy broke the law, and should be punished for it. But there's a moral to this story: don't go breaking into people's houses, because you never know if you're going to meet the neighborhood psycho. Sometimes you get the bear, sometimes the bear gets you.