Self-defense (gun-control hypothetical) scenario

I wanted to ask this in the Good News Guns thread, but it just didn’t fit there. I was inspired by Gray Ghost.

His Post:

I’m not looking to derail this thread (or thread-shit). This actually brings up an interesting question. I’ll spoiler it because this may be the wrong place to ask it.

You are at your business and a licensed/legal gun is available to you for protection. Three men approach, one brandishes a gun and states the intent is to rob you or kill you if you resist.
You pull and fire first and he goes down and won’t threaten anyone further.

Million Dollar Question: How do you know the other two aren’t armed? They could just have their hands free to carry stuff. If they both start reaching fast toward their back belt, you’ll probably get one, but both?
You just shot/killed their friend so if they have guns and if they pull them, they Will kill you.
Assume that… if they make movements and aren’t armed… and you shoot them… the people representing The People of your state will NEVER let you out of jail.

**Extra Credit: ** One says he gives up and falls to the floor but lands on top of the gunman’s gun. He’s on his belly, moving around a little and saying “don’t shoot me”, but you notice his hands are underneath him and you can’t see them.
The one still standing is making a quick reach to his back belt to either a gun or maybe just a camera phone?

Either way, Tenth of a second to think, and it will all be over in 3 seconds…
tick-tock

Yes, the law varies from location to location, but its still an interesting question because no matter what you choose, your life will never ever be the same again.