Bad news all around really, I'm sure the shooter is in pretty rough shape right now as well. It's a tricky situation, do you go out guns blazing, or you do you yell I've got a gun speak now (or something maybe not so PC lol) or I will be forced to use it.
It's a moment when you are more scared than you have ever been in your entire life, it's hard to say what you would or should do.
One thing that has me wondering, is how did the kid go into the wrong house? (Was it locked up and he broke in?) If he was NOT in the house but only on the porch....well then the home owner should probably be in trouble. If someone is trying to get into my house I'm giving the wife the phone and I will yell to get the hell out of here the cops are on the way. Should they enter, that's on them....
I once had a situation while working at a gas station in high school. A buddy of mine and I were chatting rather late while I was working one night and a guy came in. He kept saying you know what I need...You know what I need....we were both convinced without a doubt that he was going to rob the store. But thankfully before we both jumped him, we figured out he was VERY VERY drunk and just wanted me to call him a cab. So mistakes can happen, some you can take back and some you cannot. Be damn sure (but don't take too long) before you let the rounds leave.
Tragic incident all around....