On 1–5 September 1939, in the first days of the German invasion of Poland, which started World War II, the German Luftwaffe raided Koluszki multiple times. On September 1–3, many inhabitants fled, and Polish anti-aircraft artillery shot down six German planes. On September 6, the Germans entered Koluszki and the occupation began, Koluszki was annexed directly to Germany and its population was subjected to various repressions, including mass arrests, deportations to Nazi concentration camps and murder. Mass arrests of Polish intelligentsia, including teachers, were carried out on November 9, 1939 as part of the "Intelligenzaktion". Nevertheless, it was a local center of the Polish resistance movement, and Polish partisans were active in the area.