If you have to shoot...

[randy]

When you have to shoot, shoot. Don't talk.

Gee, wish I'd said that

[Malthorn]

Being on a hospital bed/gurney sounds better than a holding cell when the adrenaline runs out. Having third party reports of any damage you took could also be helpful.

[Whirlibird]

If possible, get the encounter on tape, 911 is handy for that, being a permanent retention piece of evidence. Especially if you are screaming, "Stop, drop the X!!!!".

After the action is over, definitely call the janitors at 911. Make a simple statement, some one broke in, tried to kill me, etc.

Give your name, address, a brief physical description and say that you are armed. Give your physical location, the bedroom for example.

Stay there.

Once the police arrive, give the same brief statement, include any particular things like one got away but dropped his gun by the neighbors hydrangeas.

Ask for an ambulance to go to the hospital as you aren't feeling well and ask for a lawyer.

At that point, shut up.

Yes your gun will be taken as evidence.

Do not say anything to the doctors or nurses.