where a guy went through a training program before handling a gun as security backup (or something like that). He's totally surprised after the training because he thought he was pretty good at handling violent situation.
For a split of second, you need to make the decision as who you want to wound or kill and it is hard.
For a police office to shot to kill, he only needs to (feel to) be threatened, for a civilian in that situation, you have to deal with a lot if you did kill or wound someone who is not the criminal.