Thirty-eight people were wounded and several shops and cars were also damaged in the 3 p.m. explosion in the northern village of Kugjeli, according to a police officer in Ninevah Province, who spoke on condition of anonymity because he was not authorized to speak to journalists.
Most of the victims were inside their homes when the bomb exploded near the main street of the predominantly Shiite village, about three miles east of the city of Mosul.
In the Baghdad attack, a bomb was placed at the gate of a billiards hall in the central district of Karrada. Four civilians died and 15 were injured, all of them youths in the hall, a police officer and a hospital medic said. Both spoke on condition of anonymity because they were not authorized to speak to the media.
A bomb in the same area wounded four police on patrol.
In southwest Baghdad, a bomb planted on a car killed two people, including a junior Cabinet official, and injured 11 others, including the wife and child of the official, police and hospital officials said.
Violence remains at low levels in Iraq compared with previous years, but bombings continue to kill scores of people. The attacks have raised concerns as the U.S. military draws down troop numbers and Iraq prepares for parliamentary elections on Jan. 30.
U.S. combat troops in Iraq completed a withdrawal from urban areas to outlying bases at the end of last month, ahead of a planned pullout by all American forces by the end of 2011.
Separately, the U.S. military said an American soldier in Iraq shot and killed a truck driver, an Iraqi citizen, who did not respond to warnings to stop on a highway north of Baghdad.
The shooting happened at around 2:15 a.m. on Friday when the truck approached a U.S. logistics convoy that had stopped because one of its vehicles had broken down, the military said.
Soldiers flashed vehicle lights and shouted for the truck to stop, but it continued to accelerate, according to the military. A soldier thought the convoy was under attack and fired on the truck, the military said. A teenage passenger in the vehicle, identified by Iraqi officials as a brother of the driver, was not harmed.
Maj. Derrick Cheng, a U.S. military spokesman, described the killing as "tragic" and said the soldier acted in line with terms of a joint U.S.-Iraqi security deal. The soldier was unlikely to face any Iraqi prosecution because the security agreement allows for U.S. jurisdiction over American soldiers in cases when they are on duty and outside their bases.
U.S. and Iraqi forces were jointly investigating the incident, which occurred between the cities of Tikrit and Balad.
An Iraqi police officer and a medic said the truck driver was taken to a hospital in Dujail, where he died of his wounds. They spoke on condition of anonymity because they were not authorized to speak to the media.
Such incidents were common in the early years of the war in Iraq, deepening hostility toward U.S. forces. Diminishing violence and a more culturally sensitive approach by U.S. forces since 2007 have helped appease large segments of the population and isolated militants.
The U.S. military also reported the death of a civilian Iraqi motorist in a head-on collision Thursday night with a U.S. Army Stryker vehicle, the lead vehicle of a U.S.-Iraqi convoy in western Diyala province. The convoy slowed to let the car pass and the Stryker driver signaled with the horn and headlights, but the car did not alter speed or bearing, the military said. At least one soldier in the Stryker was injured.