A man trying to do the right thing was shot and killed in Arlington, Texas today while attempting to apprehend a man who had just shot and wounded his girlfriend at her job.

As a student of armed self-defense, this is pretty much my nightmare.

An armed Good Samaritan was shot and killed outside a Walgreens in Arlington Monday, after a woman was shot during a domestic dispute in the same parking lot, police said.

Arlington police said they received the call about 11:50 a.m. about the incident, which took place at a Walgreens on New York Avenue near Southeast Green Oaks Boulevard.

The incident apparently began when a man went to the store, where his wife or girlfriend works, and the two got into a domestic dispute. Police Lt. Chris Cook said the suspect shot her in the leg or ankle during the argument.

The Good Samaritan witnessed the dispute and went to his car to retrieve a weapon, police said, confronted the suspect and tried to make a citizen’s arrest. The suspect, who had returned to his vehicle in the parking lot, got out and gunned down the Good Samaritan, police said.

Our Good Samaritan (“Sam” for our purposes) witnessed a violent crime with a firearm and decided to intervene. Not having his weapon on him, Sam went to his car and retrieved his firearm. By the time Sam retrieved his firearm, the suspect had already returned to his car and was attempting to escape.

Sam attempted to make a citizen’s arrest, but the suspect was non-compliant. Sam allowed the suspect to get out of his car, and then allowed the bad guy to raise his gun and kill Sam in front of his wife. The suspect then successfully fled, only to surrender to police several hours later. Based on all initial reports we’ve read of the incident, Sam did not apparently fire a shot at the suspect at any point in the confrontation.

Why did Sam, who appears to have had the drop on the suspect, fail to fire a shot at a known armed  and violent criminal who failed to comply with orders from him?

I wish I had a simple, easy answer for you, but I don’t.

What I can tell you is that I’ve seen it happen again and again in force-on-force scenarios, even among highly-trained shooters. Here’s one example of that happening, in a scenario that I know very well. In Gunsite Academy’s 350 Intermediate Pistol course, they run a scenario where a student armed with a Simunitions (wax bullets) handgun enters a building, and encounters a man stabbing another man to death.

What happens next depends entirely upon the reaction of the shooter.

When I took the class last fall, my scenario ended with me putting four bullets transversely through the heart and lungs of the bad guy as soon as I processed the threat and made the decision to act. It was about 3-4 seconds from first contact to the bad guy slumping over “dead” and me deciding that four rounds was enough to solve this particular problem.

But I’ve also watched numerous iterations of this exact same training scenario, and none ends the exact same way. Quite a few people shoot the bad guy until he stops being a threat, but there is also a marked hesitation among many, if not most good people to shoot other people even when those other people clearly deserve to be shot, like we see in the two videos below.

It is also common for people to fail to shoot the bad guy enough times to end the threat quickly and decisively, which then can turn an incident that should have been over quickly into a shootout that threatens everyone in the environment.

I’ve seen this reluctance to fire again and again in training scenarios and in camera footage from real life events.

Shooting bad people aggressively does not come naturally to good people.

This is a good thing for our culture, which is very non-violent, but is a bad thing when violence is the tool you need to solve the problem.

If someone pulls a firearm with the expectation that the presence of their gun will force compliance from a criminal, they have the wrong mindset, and they have probably already lost the fight. If the suspect has grown up around violence, there is a decent chance that  seen numerous friends shot and survive. He is not afraid of your puny handgun and your half-hearted attempts to command him.

Before you begin carrying a firearm for self-defense, you must not just intellectually understand that you may have to kill someone with it, but be emotionally prepared to use it decisively and with overwhelming violence until the threat goes away.

If you cannot reconcile yourself with the fact that drawing a firearm may require to use it to kill someone, then you’re doing yourself a disservice, and putting your life at great risk.