When Bellamy enters the room where the prisoners are being held at the end of the Mine shaft, He sees that all the cages have been unlocked and opened and the prisoners released. The camera pans back and up giving a view of all the vacant cages on different levels of the room. You can note a few cages hanging from the ceiling roughly 15 to 35 feet from the ground,that are unlocked (Chains and Locks visible and hanging) and opened. These cages have no clear path to them, neither from climbing or catwalk, as they are hanging in the center of the room. Any captives that were somehow released, Would have suffered severe injury or even death, with the impact to the concrete floor. The room was completely empty except for Maya's deceased father, when they arrived.