@Cvaughan is right: call 911, explain what happened in a calm and clear manner. Keep it short and to the point and FACTUAL. Then invoke and wait for your lawyer before you say anything else.
the Michigan Coalition for Responsible Gun Owners says this:
Q: What should I do if I ever need to use my gun in self-defense?
A: You should first be certain that the threat is removed before you lower your guard. Then, call 911 and say that there has been a shooting. Describe the immediate need for ambulance and police (and fire department if applicable). Tell the 911 operator where you are, how many people are wounded etc. Do not have your gun in your hand when police arrive unless you absolutely must hold someone at gun point. In either case, make sure that you describe yourself and your clothing. Fight the urge to start telling your story and stick to the relevant facts that the emergency responders need to do their jobs. Even if an individual was attacking you only moments before, once the threat is removed, you should do the responsible thing and promptly call 911 so that aid can be rendered. Remember that your goal is not to kill, but to protect yourself or others from a credible threat of death, great bodily harm that could lead to death, or rape. If you effectively use your firearm, the death of the attacker(s) will probably be the result and a homicide investigation will be undertaken.
They recommend that you exercise your 5th Amendment right to remain silent and also invoke your right to have counsel present during any questioning. You should answer basic questions asked in the interests of safety such as "Where is he?" "Where is the gun?" "What is your name?" "Are you hit?" etc., but they do not recommend that you discuss details until you've had a chance to reflect, calm down, and seek counsel.
We all hope to never need this guidance, but it's best to have it and not need it than to need it and not have it.
Best,