Complex sentence: He was slain by the Nazis on 10 Kislev, 5702 (30 November, 1941) who brought him and numerous other Jews into a synagogue, poured gasoline on it, and set it ablaze, burning everyone alive.
Split into simpler sentences: He was slain by the Nazis on 10 Kislev, 5702 (30 November, 1941). They brought him and numerous other Jews into a synagogue, poured gasoline on it, and set it ablaze, burning everyone alive.