That wasn't worded the best. What I meant by comprehension is that I think even in a situation of self defense it wouldn't be an easy task for most people from a mental standpoint. Not that I don't think it's justified.
Reminds me of the recent epidemic of police officers not taking action. Recently caught on video standing outside of the elementary school while the killer had his way.
I have trouble feeling any sympathy. It's a difficult task, but part of the sacrifice of taking the career as law enforcement. At our school, the officer had no hesitation and took out the shooter within minutes of gunfire. It's not a career for everybody.