British rule marked, however, a period of growing unrest. Arab resentment at British rule and the influx of Jewish immigrants (by 1948 one in six Jews in Palestine lived in Jerusalem) boiled over in anti-Jewish riots in Jerusalem in 1920, 1929, and the 1930s that caused significant damage and several deaths. The Jewish community organized self-defense forces in response to the 1920 Nebi Musa riots and later disturbances; while other Jewish groups carried out bombings and attacks against the British, especially in response to suspected complicity with the Arabs and restrictions on immigration during World War II imposed by the White Paper of 1939. The level of violence continued to escalate throughout the 1930s and 1940s. In July 1946 members of the underground Zionist group Irgun blew up a part of the King David Hotel, where the British forces were temporarily located, an act which led to the death of 91 civilians.