 An estimated 400,000 Jews, representing about 30% of all the city's population, were pushed into an area which took up approximately 2.4% of the city's area.On top of extreme overcrowding, inadequate food supply and disease caused tens of thousands of deaths before deportation even began.In October 1941, the German occupation administration in Poland issued a decree that every Jew, captured outside the ghetto without a valid permit, would be executed.