UPDATE!
MOM IS FINE. REPEAT, MOM IS FINE.
There was a weird guy wandering around the library, but that's sort of normal. Then at about 12:45 he grabbed a woman from behind and held scissors to her throat and started yelling "This is a hostage situation, I have three demands, call the police.”
Mom was in the stacks and was able to get to the door to Tech Services, which is downstairs and has an outside exit. She asked if she could bring patrons downstairs. They said yes and she started getting people downstairs and out of the way of the guy who was yelling and dragging the woman towards the front of the library. It’s pretty scary because she was moving around the library when the guy was moving around too. She says he was yelling about his demands and something about his father is a pastor and he deserved to go to hell. There's a theory that he was trying for suicide by cop.
So, they all stayed downstairs, along with all the staff who could get there without going through the guy, until the police came. They evacuated the building and the guy was sitting inside the east entrance with the woman in his lap holding the scissors to her neck. Eventually, they were able to fire a bean bag round at him and get him to drop the scissors and then they got the hostage to safety and took him into custody. They were only outside for about an hour, then they came back in and the city brought in a trauma counselor.
I think she was quite heroic and I'm very proud of her. But let's not do this kind of thing again, 'kay?