The attack took place when a truck bomb exploded near a car dealership in the area of Baladruz, about 30 km east of Baquba, the capital city of Iraq's eastern Diyala province, a police source told Xinhua.
The blast also destroyed about 14 civilian cars and the Iraqi security forces sealed off the area to prevent more attacks, the source said.
Iraq is witnessing its worst violence in recent years. According to the UN Assistance Mission for Iraq, a total of 8,868 Iraqis were killed and more than 18,000 others were wounded in 2013.