In 1940 a secret production of thermal ticking time bombs was started. On 28 October 1943 the soldiers of the Home Army brought death to Edward Sommer – a factory’s director. As a requital, the group of the factory’s workers was arrested who were supposed to be shot along with other residents of the city. As a result of provocation of the Home Army the hostages were released. 20 prisoners of Pawiak died instead them and they were executed on the market square in the so called Execution Site.