Zyklon B
The actual delivery of the gas to the victims was always handled by the SS. This was accomplished by a special SS unit known as the "Hygiene Division" which would drive Zyklon B to the crematorium in an ambulance and then empty the canister into the gas chamber. The Hygiene Division was under the control of the Auschwitz Medical Corps, with the Zyklon B ordered and delivered through the camp supply system.