They were old enough to know to not tolerate this. They were supposed to lock themselves in the backroom and call the police immediately to have her arrested. Then find themselves a new job elsewhere. You can get another minimum wage job within the same hour since there's so many job openings.
I blame the two workers for entertaining her. We will face crazy people, strangers or even relatives, in our lives, most not as crazy as her though but you still treat them the same way. You never ever entertain them. You cannot win against a trauma filled person or someone with mental illness. Right away you know she came from a dysfunctional household. You automatically lose entertaining her. Let the police handle it. Very unfortunate that people allow BS in their lives when they have every way of eliminating it.