A recording from the phone guy, which the player hears on their first night, says that the animatronics used to roam the restaurant freely until an incident known as "The Bite of '87", when one of the animatronics bit out a customer's frontal lobe. This has been suggested to be Foxy in Pirate's Cove, which would explain why it's closed and why Foxy has a broken jaw. He also says that if the animatronics see any humans after hours, they'll see them as an endoskeleton without its costume on and forcefully put them in the costume (killing the human). It's possible that the children roamed in Freddy's while the animatronics were roaming, and the animatronics forced them into the costumes in the backstage, however the Phone Guy claims they only react that way after hours.
