So, what happens? There are some good posts here that cover the subject well.
I'll tell you this: The call we receive from dispatch usually gives us a decent idea of what we're headed in to.
What do you do? As has been mentioned before, make sure you are not in danger. Do not put yourself in the position where the perp can get to your firearm.
If you can call from a cell phone and can be outside in plain view, while you are keeping an eye on the person who got shot, so much the better.
When we come up, if we see you, the good guy, standing outside with your hands empty, our approach will be as low key as possible. If we do NOT see you, hopefully you're still on the phone with Dispatch, and you can assure them that you're OK.
If you are NOT on the phone--and we cannot see you--then we (knowing that shots have been fired already) will be entering the home with the possibility in our minds that you might be in danger, from a possibly armed criminal in your home. Thus, we will clear the house.
I have mentioned this to make sure that there is no mistake that the BEST way for the police to contact you in this case is with you in the open, and with empty hands.
I will also say this much: When we arrive, the only thing we know is that someone has been shot, possibly killed; you are the one who did the shooting, and that you have access to a firearm. The pieces of the puzzle we can put together from that point may make the difference between you going to jail that night, or not. If it is a VERY clear cut case of self defense, then there is a good chance that you will not be arrested or detained.
Understand that we know full well that you have the right to remain silent, and the right to consult with counsel.
However, let me paint a scenario for you. In this example, I have received a call of shots fired at your residence. I arrive (with plenty of backup), and see you standing on your porch--or seated. Lying out of your reach is a firearm. I will secure the firearm, ask you to stay put with another officer, and we will take a look at the person who got shot. Aid will be summoned, as well as my supervisor.
I will approach you, and ask if you're hurt in any way. I'll ask if you need medical attention as well for any reason.
If you're OK at that point, I will then read the "Miranda" admonishment to you before you say ANYTHING.
If you decide after hearing the admonishment to fill in some of the blanks, and summarize what happened, that's fine. If not ("Officer, I'd like to consult an attorney before I say anything") then that's OK as well.
Understand this well: there is a good chance that you will be detained on suspicion of manslaughter, however it goes. Our place is not to determine guilt or innocence; once probable cause has been established, we deliver you to the trier of fact (the Court) who will make the determination.
There is one other thing to be well aware of: You can be cleared of criminal charges--but the CIVIL trial will almost surely follow.
Hiding in plain sight...