In 1939, after the Nazi occupation of Poland, he fled with his family to Soviet-occupied Lvov (today Lviv, Ukraine). He was put in charge of the literary section of the Lvov State Jewish Theatre. When Germany went on to attack the Soviets in 1941, Kacyzne tried to escape the Nazis and moved farther east to the also Soviet-occupied city of Tarnopol (today Ternopil, Ukraine). By the time he arrived, the Nazis had already occupied Tarnopol. Kacyzne was beaten to death by Ukrainian collaborators during a pogrom directed against the town's Jewish population on 7 July, 1941. His wife Khana was murdered in the Belzec extermination camp, while his daughter Sulamita survived by hiding in Poland as a non-Jew.