The Soviet authorities, having gained control over Estonia, immediately imposed a regime of terror. During the first year of Soviet occupation (1940–1941) over 8,000 people, including most of the country's leading politicians and military officers, were arrested. About 2,200 of the arrested were executed in Estonia, while most of the others were moved to Gulag prison camps in Russia, from where very few were later able to return alive. On 14 June 1941, when mass deportations took place simultaneously in all three Baltic countries, about 10,000 Estonian civilians were deported to Siberia and other remote areas of the Soviet Union, where nearly half of them later perished. Of the 32,100 Estonian men who were forcibly relocated to Russia under the pretext of mobilisation into the Soviet army after the German invasion of the Soviet Union in 1941, nearly 40 percent died within the next year in the so-called "labour battalions" of hunger, cold and overworking. During the first Soviet occupation of 1940–41 about 500 Jews were deported to Siberia.