Mass killings

The Khmer Rouge killed people they classified as enemies of the revolution: former government officials, soldiers, intellectuals, professionals, ethnic Vietnamese and Chinese, Muslim Cham, Buddhist monks, and eventually members of the Khmer Rouge themselves who were suspected of insufficient loyalty. The S-21 prison (formerly a school) became the regime's main torture and execution center. Approximately 20,000 people were imprisoned there; perhaps 12 survived.

Mass killings occurred at sites that became known as the Killing Fields. Choeung Ek, outside Phnom Penh, is the best-known. Victims were typically killed with farm tools or buried alive to save ammunition. The Killing Fields are now memorial sites that Cambodians and international visitors can visit; the bones of victims are still being recovered.