The Nazis killed millions of people, hundreds at a time, with poison gas in special rooms called gas chambers. They forced others to dig giant holes in the ground where, after days of hard work, Jews and other prisoners were shot, buried, and burned in a mass grave. The Nazis executed many others by shooting, stabbing, or beating them to death. Still, others died in forced marches from one camp to another. Many other people died of starvation, diseases, and freezing to death because of the terrible conditions in the concentration camps.