When an armed robber approaches you with a weapon, you are legitimately in fear of death or grievous bodily injury. You have a legal right to take whatever steps are needed to eliminate that threat, up to and including killing the robber. That is state law - it has nothing to do with the chief of police.
BTW, how do you think the West became "un-wild?" Ever hear of what happened to the Dalton Gang in Coffeyville? There were hundreds of similar events. The most certain way to stop crime is to kill the criminal, and if you are within your legal right to do it, you're a fool not to.
More information about formatting options