The attack took place about 28 km (17 miles) north of the capital, between the towns of Tarmiyah and Mishahda. The area has been the scene of clashes between Iraqi forces and Islamic State in Iraq and the Levant (ISIL) fighters, who have taken control of large sections of northern and western Iraq this year.
In other violence, four Iraqi soldiers died in a friendly-fire incident in the town of Udaim, 90 km northeast of Baghdad, Reuters reported.
The soldiers, who had been wounded by ISIL terrorists, were being taken to hospital when Shiite militia volunteers who mistook them for insurgents fired a rocket-propelled grenade at their vehicle, police and medical officials said.