This is the story of an Active Shooting in a Texas church, and a man who probably asked for God's help to protect his neighbors.
This is my inference, because the location was a church, and Jack needed to make an accurate shot to (a) take out the gunman and (b) not hit innocent bystanders.
This brings up the age old question of accuracy vs. speed, and what it takes to get a clean shot to the central nervous system.
I like to use the movie
Unforgiven as an example of discussing what it takes to be a successful gunfighter. Like the story of English Bob killing Corky "Two Gun" Corcoran. Bob shot at Corky, but was drunk and missed. Corky panicked and missed his shot, too. Bob tried again, and missed again, because he was still drunk! Corky, then took careful aim at Bob, pulled the trigger, and his Walker Colt blew his hand off ("which was a failing common to that model"). Bob walked over to the unarmed -- and one-handed -- Corky, and shot him right through the liver.
He then explained how being under fire changes the situation, that most people will hurry and miss. It's also difficult to shoot another man even if you're not under fire at the time.
Basically, it's counter-intuitive for a rational, moral human being to point a firearm at another and pull the trigger. So, being able to do that while being fast and on target takes a well-trained and disciplined person .... or a psychopath who isn't concerned with the other person's life.