It may be a cliche but frequently “A Good Guy with a gun stops a Bad Guy with a gun”, and this video provides quite a good breakdown of the situation to serve the example.
A customer at a grocery store is present while an armed robbery is occurring. The customer reacts and draws a concealed firearm which he discharges wounding the suspect and ending the altercation. The narrator does a reasonably good job evaluating the situation, though one thing I did notice was the customer at 1:25 present his pistol, which the suspect does not see I think because of his hood, then go back to a low ready, only to re-engage and discharge multiple shots. A variable may be off-camera, but to me it looked like the armed customer had a clearer line of fire, and earlier opportunity to engage the threat. Did the customer hesitate or did he have reason to hold steady?
What did you pull from the video?
Train well, train consistently