Zyclon B was used by agents of the Third Reich to perform mass assasination in batches, in concentration camps. It was combined in crystal form with water and formed lethal gases which were flooded into "shower rooms" in which hundreds of prisoners at a time were locked until they all died. They were then shoveled into mass graves and the process repeated with a new batch. The prisoners were typically Jewish or Gypsy, although other groups were not excluded.

A