When the arrests began at the end of June 1941, the Ustasha needed a place to keep the arrestees until the deportation to other camps. Due to the war, the space of the Zagreb Fair was empty, without any exhibitions, and because of the spaciousness of the pavilions that could keep large numbers of people, the NDH authorities turned it into a transit camp. Besides, then, as well as now, the railway passed by both sides of the Zagreb fair, its industrial tracks enabling the transport of goods to and from the pavilions. This also made easy the transport of people from the transit camp to other camps throughout the NDH. The inmates were first transported to Danica Camp, then to Gospić Camp System (Gospić, Jadnovno, and the island of Pag camps Slana and Metajna), and since summer 1941 to the newly-opened Jasenovac Camp System.