Complex sentence: The doctors reveal that the "creatures" were escaped patients, and after realizing that Amanda "knows too much," she is then forced into a dark cell and is swarmed by the recaptured patients, as the doctor closes the door's viewing shutter.
Split into simpler sentences: The doctors reveal that the "creatures" were escaped patients. Amanda is then forced into a dark cell and is swarmed by the recaptured patients, as the doctor closes the door's viewing shutter.