I remember when my school librarian used to yell at everyone to shut up and stop bothering the other students, and then yell at everyone to shut up and stop bothering the other students. I think she was there late at night, all alone, yelling at everyone to shut up...
Shhh
I had a high school librarian like that. She would zero in on the people who were studying, actually using the library for what it was for. Threaten them with a vice-principal office visit then throw them out. Why she knew they would leave!