These situations remind me of the last Field Exercise I was in. Basically, it involved a motorist in distress distraction\ambush.
During debrief a teammate commented that no one said civilians were going to be involved. I replied that it was implied in the initial briefing when they said "local sympathizers".
After that, it became a huge can of worms 'cause now the impression among the team was everyone and everything is a potential threat. In a way, I get that line of thinking. However, there's a basic rule that we fall back on when the rules of engagement isn't all out war. If it's shooting at you, it's hostile. More commonly, don't engage unless fired upon.
It sucks to be in a situation where that is the rule, but realistically, it prevents these results. As a permitted carry individual, it's one of those things that should be hard-wired as well. This rule seems to be lost on individuals that end up getting headlines though.
I get it, one wouldn't want an individual killed because of failure to act, but the use of lethal force is a decision that must be made with absolute certainty. Where the immediate threat isn't directed in ones direction, there is time to evaluate. While a threat is imminent, if not carried out immediately, there is time to evaluate. If one comes up on an imminent threat situation that wasn't personally witnessed, one does not have all the information for this situation. The mere presentation of a firearm does not necessarily indicate an imminent threat. Most people aren't willingly unresponsive to threat of injury or death so unresponsiveness in such a situation should be evaluated.
Think back to the shootings of law enforcement in Texas where armed citizens responded as officers were being shot. None of them were shot by law enforcement though some were mistakenly arrested. Case in point for carry States BTW, but the point is those officers didn't respond to imminent threats by firing at them.