When I took my CCW class, they hammered it home that if you are ever involved in a shooting, ask for a lawyer and keep your mouth shut, no matter what the circumstances. As the above poster mentioned, things happen, and people with ulterior motives can find ways to trip you up.
My CCW instructor also mentioned that as LEO's go through their classes, they are also taught to be quiet and ask for a lawyer - and not discuss the shooting with other LEO's. So it's the same advice for all parties concerned, for your own protection.
He also mentioned the "time compression" phenomenom. In high stress, what seems like 10 minutes can be 30 seconds of real time. People get excited, don't know about this, and talk their heads off. It comes back to haunt them in court, they appear as an unreliable person or a liar if they get the time sequence wrong. Which they almost always do, because of this. Better to be quiet and ask for a lawyer.
It's too bad we have to think this way, but that's the way it is these days.