Belzec was the first of the three Operation Reinhard killing centers to begin operations, and it became a model for the others. Built on the site of a former labor camp in the Lublin District, between Zamość and Lwów and chosen for its rail connections to regions with large Jewish populations, it was run by a small German staff of roughly 20 to 30 and a Trawniki-trained guard unit. In barely nine months of operation in 1942 the camp murdered approximately 434,500 Jews, mainly from the Galicia, Kraków, and Lublin districts, making it one of the deadliest sites of the Holocaust relative to its brief existence. Its first commandant, Christian Wirth, pioneered the killing operations later replicated at Sobibor and Treblinka. The camp was dismantled and disguised as a farm by mid-1943, and because only two prisoners are known to have survived, Belzec remains among the least documented and most haunting of the killing centers.