Following a false message that the Judean provisional government had come to terms with the Roman Army, delivered by the Zealots to the Idumeans, a major force of some 20,000 armed Idumeans arrived to Jerusalem. It was allowed in by the Zealots and thus, with Idumeans entering Jerusalem and fighting by the side of the Zealots, the heads of the Judean provisional government, Ananus ben Ananus and Joseph ben Gurion, were killed with severe civilian casualties in the notorious Zealot Temple Siege, where Josephus reported 12,000 dead. Receiving the news of the carnage in Jerusalem, Simon bar Giora left Masada and began pillaging Idumea with his loyal troops, setting his headquarters in Na'an; he met little resistance and joined forces with Idumean leaders, including Jacob ben Susa.