Just a quick comment based on my years wearing a badge. IF you hunker down and call 911 and expect the police to come in and clear your house for you, may I suggest what will likely be the response relayed through the 911 operator?
911: "Police are outside your home sir."
Me: "I think there is someone inside my home."
Questions back and forth about the situation...
911 "Where are you sir?"
Me "I'm in my bedroom with my family."
911 "Do you have any weapons in your home?"
Me "Yes, I have a shotgun and my wife has a pistol."
911 "Ok...ah sir, we'll need you to lay your weapons down and come out the front door with your hands where we can see them. We wouldn't want to shoot you by mistake."
Me "But there is a bad guy in my home and my wife and children..."
911 "Sir, let me repeat..."
And so it will go. In my experience, what will happen next is a cordon around your house, summoning of a SWAT team, lots of sitting around and waiting for the sun to come up, the news media will swarm, and the encounter will go generally downhill from there. Why? Because, as has already been said, the police will not enter a darkened home with known armed people inside fearful for their lives. Too much chance of tragedy. If you are lucky, you might get them to help you out through the window where you are hunkered down.
I think if nothing else, this thread proves that all of us need to have an individual plan for the possibility of what has been discussed. Only generalizations will work for all of us. We had better think through specifics that fit me now. Thanks for an informative discussion.