The first mass transport—of 728 Polish male political prisoners, including Catholic priests and Jews—arrived on 14 June 1940 from Tarnów, Poland. They were given serial numbers 31 to 758. In a letter on 12 July 1940, Höss told Glücks that the local population was "fanatically Polish, ready to undertake any sort of operation against the hated SS men". By the end of 1940, the SS had confiscated land around the camp to create a 40-square-kilometer (15 sq mi) "zone of interest" ("Interessengebiet") patrolled by the SS, Gestapo and local police. By March 1941, 10,900 were imprisoned in the camp, most of them Poles.