During the joint German-Soviet invasion of Poland, which started World War II, in 1939, Pionki was bombed by the Luftwaffe and afterwards the Germans occupied the town. In addition to the other destruction, the Germans brutalized the Poles and the small Jewish population of around 200. As part of the "AB-Aktion", in June 1940, the Germans carried out mass arrests of Poles, who were afterwards imprisoned and tortured in Skarżysko-Kamienna and then murdered in a forest near Skarżysko-Kamienna. Many Jews were conscripted for slave labor including the most dangerous jobs at a local gunpowder faculty. In late 1941, a ghetto was established and Jews from surrounding towns brought there, resulting in a population of around 700 and such severe overcrowding that some people lived in the street. Some local Poles were helpful in providing food for the impoverished residents. In August 1942, some of the healthier workers were sent to live at a work camp while the rest were sent to the Zwolen ghetto and then, in late September, to the Treblinka extermination camp. They were immediately murdered there by gassing. The number of Pionki Jewish survivors was small, but at least eight. In April 1944, the Germans executed 10 Polish resistance members in Pionki.