Initial report filters down to me that a man has fallen in the upstairs men's room. Will I investigate? Yes, I will investigate!
I go to the upstairs men's room and it is empty except for the handicapped stall. It is easy to see that under the partition a man is lying on his back. His head appears to be somewhere near the base of the toilet and he is moving around just enough to suggest life and consciousness.
I tap lightly on the door. "You okay in there?" I ask.
"I'm good." He answers.
I report my experience around the library and to The People In Charge and check back after about 45 minutes. Whoever is in that stall now is sitting, which is more the usual and requires no knock.