Following the joint German-Soviet invasion of Poland, which started World War II in September 1939, Augustów was occupied by the Soviet Union until 1941. Many inhabitants were sent to exile in Kazakhstan, from where some were able to return after 6 years. On June 22, 1941, just before the Germans captured the town, the Soviets murdered around 30-34 Polish prisoners in Augustów as part of the NKVD prisoner massacres. The Nazi German forces occupied Augustów until 1944, and operated a forced labour camp in the town. World War II brought the destruction of about 70% of the town and death or departure of most of its residents, amongst them a community of several thousand Jews who were imprisoned in the ghetto situated between the canal and the river. The Germans executed practically all of them before they left. In 1945 the Soviets conducted the nearby Augustów roundup - a special operation against former Armia Krajowa anticommunist fighters.