Krosno was under German occupation from 8 September 1939 to 11 September 1944. On 25 September 1939, the German "Einsatzgruppe I" entered the town to commit various atrocities against the populace. As a result of the genocidal policy of Nazi Germany, which goal was also the biological extermination of Polish children, about 80% of Polish children in the area suffered from anemia. 100 Poles who were either born, lived or studied in Krosno were murdered by the Russians in April–May 1940 in the large Katyn massacre. Among the victims were many local policemen. 24 students of the local aviation school were murdered in Katyn and Kharkiv. From 1942 to 1944, the Germans operated a forced labour camp for Jews in the town.