A suicide bomber blew herself up near U.S.-allied Sunni Arab fighters walking in a crowded area of Baqouba, killing at least eight guards and injuring 24 other people Thursday, Iraqi police said.
The attack came as the U.S.-backed Iraqi military is promising to launch a major offensive in Diyala province aimed at taming the last major insurgent belt north of Baghdad.
The woman, shrouded in a traditional black Islamic robe, detonated her explosives belt about 8:30 p.m. as she approached a group of Awakening Council guards in the central New Baqouba area, a police officer said.
The officer, who read the police bombing report but spoke on condition of anonymity because he wasn't authorized to release the information, and witnesses said the local Awakening Council chief, Naaim al-Duliami, was killed along with seven of his bodyguards.
The U.S. military in northern Iraq said troops were investigating and could not immediately confirm that the attacker was a woman.
The Sunni turn against al-Qaida has been credited by the U.S. military as a key factor in driving down Iraq's violence to its lowest point in more than four years. Also cited are the U.S. troop buildup and a cease-fire declared by anti-U.S. cleric Muqtada al-Sadr for his Shiite militia.
Members of the U.S.-allied Sunni groups have frequently been targeted by al-Qaida in Iraq and other insurgents seeking to derail the security gains.
Earlier Thursday, gunmen killed three Awakening Council members in drive-by shootings at checkpoints in the Sunni neighborhood of Azamiyah in northern Baghdad, according to a leading member of the group, who spoke on condition of anonymity because of security concerns.
Baqouba and other areas in Diyala have been hit by several bombings in recent months as Sunni insurgents show they can still cause casualties. Two suicide bombers attacked army recruits at a Baqouba military camp last week, killing at least 28 and wounding 57.
Insurgents have been using women more to stage suicide bombings. Women are more easily able to hide explosives under their cloaks and often are not searched at checkpoints.