Iraqi police say a car bomb blast has killed at least 21 people and wounded 72 others at a crowded market in the northern town of Tal Afar, near Mosul.
The U.S. military says five of those injured in Friday's bombing were police officers, the others were local civilians.
It was the latest in a series of attacks in the region, where U.S. and Iraqi troops have been battling al-Qaida militants.
Separately, Iraqi officials say Baghdad and Washington are close to a deal for U.S. combat troops to leave Iraq by October 2010.
They say the proposed timeline sets an initial target for U.S. troops to withdraw from Iraqi cities and remain on their bases by the middle of next year. The schedule could be amended depending on security conditions.
U.S. officials say they have not agreed to any withdrawal dates.
They say there has been progress in security talks, but that some issues remain in dispute.
In related news, a spokesman for Moqtada al-Sadr said Friday the influential Shi'ite cleric will call on his militia to disarm if the United States begins to pull troops out according to a set timetable. Sadr has ordered several cease-fires, which are credited with producing a major reduction in violence in the past year.
U.S. President George Bush and Iraqi Prime Minister Nouri al-Maliki agreed last month to set what they called a "general time horizon" for withdrawing U.S. forces from Iraq. U.S. officials have said such withdrawals will be tied to conditions on the ground.
Iraq's government has been pressing Washington to agree to a withdrawal schedule to ensure that a security pact wins approval in the Iraqi parliament.
Some information for this report was provided by AFP, AP and Reuters.
