Anger. Anger actually blinds you
We talk about seeing red. There is a truth to that and what anger and the fight part of fight/flight can do to us. While I did not ever fire a shotgun into a group of people, I do remember a time I came close to homicide for something far stupider (a snow bank) with a large blade. Much of the work that needs to be done inside is finding ways to handle that blind rage without harming another.
This article is long, thought provoking and sometimes hard to read. If you are doing prison work, it is doubly worth reading.