The location was expanded into a prisoner of war camp for Red Army soldiers captured in the Soviet zone of occupied Poland after the implementation of Operation Barbarossa. The first of them arrived in October 1941. In the beginning, the POW camp was no more than an enclosed area. The prisoners received minimal or no food, and were reduced to eating grass and roots. There were no barracks, so prisoners had to sleep out in the open. This lack of shelter killed many prisoners during the severe winter of 1941–42. Many were tortured and mistreated, or were executed en masse at the foot of what became known as the ('Hill of death'), its real name being . On this hill the dead inmates were cremated in specially built funeral pyres.