Massacres were committed in over 30 locations across the formerly Soviet-occupied parts of Poland, including in Brześć, Tarnopol, and Białystok, as well as in prewar provincial capitals of Łuck, Lwów, Stanisławów, and Wilno (see Ponary). The survivors of mass killing operations were incarcerated in the new ghettos of economic exploitation, and starved slowly to death by artificial famine at the whim of German authorities. Because of sanitation concerns, the corpses of people who had died as a result of starvation and mistreatment were buried in mass graves in the tens of thousands. Gas vans were made available in November 1941; in June 1942 the Polish National Council's Samuel Zygelbaum reported that these had killed 35,000 Jews in Lodz alone. He also reported that Gestapo agents were routinely dragging Jews out of their homes and shooting them on the street in broad daylight. By December 1941, about one million Jews had been killed by Nazi shooting operations in the Soviet Union. The 'war of destruction' policy in the east against 'the Jewish race' became common knowledge among the Germans at all levels. The total number of shooting victims in the east who were Jewish are around 1.3 to 1.5 million. Entire regions behind the German–Soviet Frontier were reported to Berlin by the Nazi death squads to be ""Judenfrei"".