Ok, but how would you know it was a prank? If you have someone who has suddenly entered into your personal space exhibiting erratic but persistent confrontational behavior, I think there's some justification towards reacting with violence. I dont think most of us are conditioned or trained to react to threatening behavior in the most effective way, like cops and military are. So that means flight, freeze, or fight. You don't have the benefit of knowing it was a prank, you just have a situation rapidly unfolding in front of you. Unfortunately in this situation Colie was armed, and responded with that measure. I think most of people would be ok if the response was just a phsyical fight without a gun, but then again how many people have the capability to "win" that way?