The Warsaw Ghetto Uprising describes how in 1940, the Nazis forced over 400,000 Jews into a walled area of Warsaw called the Warsaw Ghetto. By 1942, over 12 families were crammed into each three-story building due to overcrowding. A resistance group called the ZOB formed among the Jewish youth in the ghetto. They stole weapons from the Nazis like machine guns and Molotov cocktails and used them to fight back against the Germans when they began deporting Jews from the ghetto to concentration camps.