You seem to be standing in a rather large room, 10 meters wide and 30 meters long. The reading area you're currently in, was filled with several empty tables and chairs, and located close to the door you used to come in. The far end of the room was filled with rows upon rows of shelves, filled with dimly glowing Memory Orbs.
Scanning the floor for potential exits and ways of entry, you spotted a total of 6 rectangular windows, on each side of the wall, and 6 more, smaller, round windows, close to the ceiling.
There were 2 doors, close to the reading area that both led to a small reception hall and then the buildings main entrance that you used to come in earlier.
As Rain presses her ear to the door, the reception hall beyond seems quiet, but there's definitely some muffled stomping, coming from outside of the building.
Looking again toward the far end of the room you're currently in, beyond the shelves of Memory Orbs, you spot 3 different doors there. Brodeur and the other Keepers had vanished behind those doors earlier and haven't come out.
Trying to peek through the windows, you notice that the immediate perimeter of the library was vacated. There's a giant crowd of villagers gathering in the market, in front of the library. They all seemed really alarmed and listening to someone you couldn't see.
In addition, you definitely noticed at least 4 Witchers moving towards the libraries front door and fading from your angle of sight. It looks like they haven't surrounded the library yet and only aggregating at the entrance. But one by one, more Witchers are coming out of the crowd and moving toward the library, first toward the front door, then its immediate corners.
It seems only the entrance side is covered and they're just now trying to surround the building, starting from the entrance.
Kaylee pointed toward the 3 doors on the other side of the room and wanted to whisper something, before she was cut off by a piercing shriek from the market:
"-MACHINE FOLK! MACHINE FOLK ARE INVADING!!! EVERYBODY RUN!!!!"
"-QUIET!!!" someone barked in response, but the entire village had already erupted into a massive cacophony of panicked yells and a stampede of footsteps, running away from the library. Through the massive racket outside, you thought you heard a flare explode over the village.
"M-More machine folk?!" Ursula called in alarmed confusion.
"..I think they mean us" Kaylee cringed, looking around.
"-Someone call back the kings! They couldn't have gone far!!!" you heard a yell from outside the library.