Gas chambers were the efficient way of killing the prisoners, after shooting became too messy and a waste of bullets. Prisoners were often decieved that they were going to showers when they were really going to be gassed. Pellets containing the gas would be dropped into the rooms through holes in the ceilings, and usually one third of the prisoners died immeadeatly. The type of poison used was called Zyklon B, a kind of pesticide. The killing could be viewed by a small hole in the door. After the prisoners were dead, there bodies were burned, and hair, gold teeth and other items were removed from their bodies.
