My wife carries some of the time. She ducks otherwise without saying a word. Once, she had her back to the trouble and as I drew and turned her way, she was already down and clear.
Another time, she was unarmed and saw a BG drawing/shielding a gun under his coat and approaching a LEO from behind. She poked and hissed it in my ear and I was able to draw and shout out. He froze, realized I had the drop, all in about 1/2 a second. He turned and ran as the LEO turned to see the end of it.