According to his brother and an official at the Interior Ministry, Khadim Sarhid al-Hemaiyem and his family died in a spray of machine-gun fire. The gunmen, who escaped, apparently were wearing army uniforms and arrived at the house in army vehicles.
Khadim Sarhid al-Hemaiyem was the leader of the Sunni Batta tribe, which is one of the largest Sunni tribes in the area north of Baghdad.
His murder follows a push by U.S. and Iraqi officials to encourage Sunni Muslim participation in next month's elections.
In other news, U.S. Secretary of State Condoleezza Rice has told American television that conditions for a gradual reduction in U.S. forces in Iraq could happen "fairly soon."
Rice was interviewed late last night. She did not set any deadlines but said handing over to Iraqis important security responsibilities is being constantly discussed by U.S. representatives in Baghdad.