 The victims of death camps were primarily killed by gassing, either in permanent installations constructed for this specific purpose, or by means of gas vans.The six extermination camps were Chelmno, Belzec, Sobibor, Treblinka, Majdanek and Auschwitz-Birkenau.Auschwitz and Majdanek death camps also used extreme work under starvation conditions in order to kill their prisoners.