The securing of the ghetto system was preceded by a series of anti-Jewish measures as well as anti-Polish measures meant to inflict terror. The Jews were forced to wear the yellow badge. Their businesses were expropriated by the Gestapo. After the invasion of Poland, many Jews, particularly the intellectual and political elite, had fled the advancing German army into the Soviet-occupied eastern Poland and to the area of future "General Government" in the hope of the Polish counter-attack which never came. On 8 February 1940, the Germans ordered the Jewish residence to be limited to specific streets in the Old City and the adjacent Bałuty quarter, the areas that would become the ghetto. To expedite the relocation, the Orpo Police launched an assault known as "Bloody Thursday" in which 350 Jews were fatally shot in their homes, and outside, on 57 March 1940. Over the next two months, wooden and wire fences were erected around the area to cut it off from the rest of the city. Jews were formally sealed within the ghetto walls on 1 May 1940.