Before the war the building was used as a munitions bunker. From August 1940 to July 1943, the SS used it as a crematorium. In August 1941, the largest room which had been a morgue was converted to a gas chamber, the first at Auschwitz. any Jews were murdered within hours of arrival at Auschwitz. Several groups of Soviet prisoners of war and sick prisoners unlikely to return to work were also murdered this way. With the construction of Auschwitz-Birkenau II, the use of the gas chamber gradually stopped and the building was used for storage and as an air raid shelter for the SS. The incinerator, chimney, and ceilig holes were dismantled and reconstructed by the museum.