Gotta be careful here. If you are in the house and someone comes in illegally, you are typically allowed to use deadly force since it's presumed that you're at risk of imminent bodily harm. However, if someone is in your house when you're not also inside, use of deadly force would likely get you into trouble because at that point you're defending only property. Deadly force can't be used in the defense of property. So if you come home from vacation, notice someone in your house and go in with guns blazing, you're likely to catch a homicide charge.
But not if you bury the body and nobody heard the shots;-)