In Florida we are allowed to carry firearms, and I do.
My next door neighbors are mere yards away, my front door is not in view of theirs. I have cover in the form of the end wall of my home, concrete block.
I know them as friends, the Wife 30s? Husband same, and a 18 month old boy.
My first thing to do call 911, give phone to my Wife, Cell phone, grab large flashlight, throws a beam 300 ft, very bright, blind individual with it, once I see him, outside, I have cover.
When he, if he, attempts to shoot at me (the range is 7m) I would, from cover, put 9mm 147g Ranger Ts into his upper chest. Glock19 TruGlow sights.
Step back into house, have my Wife inform Police dispatch of the circumstances, she would have been on to the 911 operator from the moment I had gone (very cautiously) outside. My hearing would be ringing like bells.
Any one trying to gain access to my neighbors House, via the front door, has no cover. The young man has a 9mm pistol, so I am not going across the yard, and Police response is measured in minutes here.
So a gun in hand man is not a bright thing to be when they arrive.
Holster pistol, wait. Monitor street, look for accomplices, call Guy next door on house phone, my Wife would be on Cell.
Those are my circumstances. That is how I would respond, all things being what the scenario dictates. Worried about charges? Not in the least, this is Florida.