Start shooting Guard 1.
Please don't.
Why not?
Because the last time you started shooting it got these guys over.
What makes you think that there are people who heard the gunshots but didn't come over for whatever reason?
What makes you think that the NPC won't fire his equally loud gun himself, especially since he already fired three shots?
Really, there's little point in not shooting.
If only I could drain the life-force of my enemies with my touch, using it to heal myself or grow in power somehow (accelerate mutation speed).
((That's a strange thought to spontaneously have.))
"Oh, how I wish I could be a vampire, so I could become stronger and more horrific."
Anyway, this suggestion is a troublesome one. First, the first half implies the game relies on souls or something like that, or that you can gain life from sucking blood. The former is probably not going the happen, the latter is questionable.
The second, accelerating of mutation time is not going to happen because it is attempting to outright break "rules" I've set, and it's a bad idea anyway. Due to the rate of health drain to regen, faster mutation times means faster injury and thus will probably seriously put the character at risk of dying without any outside influence.
((Are PCs invulnerable? A baddy just rolled a 19 on sawing someone's spine, and as a result they're somewhat injured...))
Look, if I made it so called shots were far more effective, people rolling 20s against heads with stabbing weapons would probably instakill or almost kill people. Including players. Obviously, this is not a good game design decision.
People damage people proportional to their weapon and their roll. Whether their called shots do something or not is entirely arbitrary.
In theory I could make called shots have a greater effect, but then that would be completely against the point of this RTD, to have basically minimal rules. I made the same decision to not expand complexity the first time I changed how the combat system works, and I feel as though I should maintain the same stance.