Two 158 grain Remington 158 grain SJHP .357 Magnum rounds two inches apart in his chest with his t-shirt blackened my muzzle flash. When he didn't blink, I knew there was nothing I could do, besides, I was trying not to bleed out myself from some knife wounds on my off hand. Two mounted officers were there before I could sweep for additional threats. The senior of the two, a sergeant, kept the lieutenant who showed up with a bad attitude away from me while the paramedics told me how lucky I was to still have a thumb. Plenty of witnesses to the attack, and I left with my gun back in my holster. Then my wife had to stop by the post hospital on the way back to our quarters for the medics to examine what the paramedics did. My section sergeant came by our quarters that evening to pick up the profile the Army docs gave me. Going to tank gunnery with my left hand in miles of gauze, cotton, and ace bandages was no fun.
Open carry state, 'bout a hundred years ago.
If there is no further threat, I'm not injured myself, and I have someone to cover me, I might consider first aid.