A suicide car bomb struck a checkpoint manned by an Awakening Council group outside a village in Salahudin province on Sunday, killing 17 people and wounding more than 40 others, a local police source said.
"A suicide bomber rammed in the afternoon his explosive-laden car into a checkpoint outside the village of Mazarie near the townof Yathrib, 70 km north of Baghdad," the source from town's police told Xinhua on condition of anonymity.
The source said the casualties include Awakening Council members and civilians. Earlier, the source put the death toll at four, with eight others injured.
The Awakening Council groups are Sunni fighters who turned up against al-Qaida in Iraq network, cooperating with the U.S. troops and Iraqi security forces by guarding neighborhoods or providing information.
Rifts emerged between predominantly Sunni insurgent groups and the al-Qaida in Iraq organization after the latter adopted a hardline Islam and exercised indiscriminate killings against both Shiite and Sunni Muslim communities.
The U.S. military in Iraq said in the day that the newly-captured al-Qaida documents showed that the Sunnis insurgence has considerable discouraged the terrorist group.
The U.S. military showed a diary by an al-Qaida sector emir named Abu Tariq in Balad, north of Baghdad, and is a document written by a mid- to high-level al-Qaida official.
"Abu Tariq's diary provides clear and compelling evidence that the Iraq volunteer citizens' groups ... are restricting the terrorists' freedom of movement," U.S. military spokesman Rear Admiral Gregory Smith told a press conference.
"The diary shows that al-Qaida regards these groups as a grave threat and the terrorists are increasingly targeting them," he said.