3 teenagers broke into my wife's uncles house a few years ago. It was dark. Be busted off a few rounds, hit one in the back. Kid is paralyzed now.
I am not saying what he did is justified from a moral standpoint on his side, but a someone who is breaking into someones home, you have no excuse to not understand that activity may very well cost you your life.
Legally, I personally don't think there should be ramifications. They broke into his house, he shot them. Maybe if people knew that if you get caught breaking into someones house, that person cat shoot you, hack off your limbs, and toss you in a freezer, people would perhaps think twice about breaking into the homes of others.
From a moral standpoint though, I would have a hard time justifying my actions with finishing shots and such. Shoot them, a lot, them gtfo and call the cops.