According to their version of events, at around 6:00AM, Hajj Sa'ad Sa'ad Nayif al-Hatemi, chief of the Hawatim Shia tribe, led a group of armed pilgrims from that tribe to a security checkpoint. Security forces killed al-Hatemi, his wife, and his driver. The pilgrims, who had walked alongside the car to the checkpoint, then attacked the security forces in retaliation. A local tribe, the Khaza'il, tried to stop the fighting but were shot at in the crossfire. Iraqi troops at the checkpoint reported al-Qaeda forces were attacking and more security forces arrived in response, surrounding the Hawatim. The Hawatim tried unsuccessfully to stop the fighting at this stage. Firing continued and a U.S. helicopter was shot down. U.S. aircraft bombarded the area until early the next morning. 120 Hawatim and local residents were killed. The group led by Ahmad al-Hassani was based in the local area of the fighting and was drawn into it. They, the Hawatim and the Khaza'il, are opposed to groups that make "the core of the Baghdad government". The presence of Ahmad al-Hassani's group provided justification for a massacre of opponents to important groups in the Iraqi government.