The Washington Post reported the assailant, dressed in a camouflage police uniform, rushed an armored car carrying police Maj. Gen. Maarid Abdel-Hassan and detonated his explosives. The police officer escaped injury but he said another officer lost a leg. Earlier reports had said a car-bomb had targeted the conference.
"It was an ambush," Abdel-Hassan told the Post by telephone.
The blast sent body parts flying into the streets around the crowded market. The Post reported police were seen chasing a dog that ran off with a severed leg.
Later in the day, insurgents drove through the al-Amarat neighborhood of Abu Ghraib, brandishing machine guns and rocket-propelled grenades, said a National Security Ministry official, speaking on condition of anonymity.
The attack occurred in western Baghdad as tribal leaders were attending the reconciliation conference, CNN reported.
"The security in Iraq has settled down at level that allowed leaders of tribes to come from everywhere," Iraqi Prime Minister Nouri al-Maliki told those attending the gathering. "It is a reconciliation message for those who boycotted Iraq, because of the (sectarian) strife; they returned home now and we welcome them."
The bombing happened three days after Maliki urged sheiks of the nation's tribes to participate in Iraq's government in the latest official effort for reconciliation and to bring some former members of Saddam Hussein's Baath party into the political arena, CNN said.