The only time I was ever afraid someone might pull out a gun was at the big hospital. One of our techs had been fired (and we were told that she was banned from the property unless she was a patient) and a couple weeks later, her scummy boyfriend showed up at the window. It turned out he had some paperwork that our boss had to sign regarding her unemployment claim, but I ducked into a back room and made sure I had several walls between him and me, and a phone in my hand.
She was a nice person, too, who had the misfortune to grow up in a family where most of them spent their adult lives in and out of prison. 🙁