On gun fora and blogs around the Intertubz, there has been endless discussion on how one should act after a self-defense shooting. You might want to take your lesson from these two Winston Salem, NC police officers who were recently involved in a shooting:
Police said Friday afternoon it appeared the only shots were fired by the officers, though the officers haven't been questioned since they attained lawyers.
Yes, the cops have lawyered up, and in a similar situation, so should you. That's not to say you should be an ass about it at the scene. However, as a part of their training, police officers are taught what happens to a person in the aftermath of a shooting--the shakes, the urge to babble on aimlessly and so on. The best training also teaches them to dummy up fast and lawyer up just as fast.
Your best move is to give the responding officers a very brief account of the events, point out witnesses and evidence and then tell the officers that you hope they understand, but you've just been through a very traumatic event and that you'd like to be checked over by medical personnel. Unless everyone is pointing at you and saying "BAD GUY!", this will immediately buy you time, since it's a reasonable request they can hardly refuse without looking bad in court. Use that time to forcefully collect your wits as best you can. Ask for something to drink and a place to sit for a moment. These are also reasonable requests that they will have a difficult time refusing. When they decide that they've been reasonable enough and start questioning you, then you hit them with "Officer, I hope that you will understand, but given the traumatic event that I've just went through, I'd like the advice of my attorney before speaking with you any further." And then dummy the hell up.
They won't be happy with you, and may even start to step outside the boundaries and give you the line about "If you haven't done anything wrong...." Be polite but firm in your refusal to talk, even if they arrest you.
The freedom you save will be your own.