The bomb had been placed on the main Khanaqin-Halwan road, nearby an Iraqi army observation post.
"The bomb was triggered by a truck at 10:30pm, wounding the driver and two others," Salar Nisaif, in charge of bomb disposal teams at a Hashd al-Shaabi regiment, told Rudaw.
He questioned how the perpetrators had not been noticed by the Iraqi army since the bomb was so close to their post.
At least six bombs have blown up in Khanaqin in the past week, killing two and wounding 11.
Khanaqin is one of the territories disputed between Baghdad and Erbil. It has seen ongoing threats from ISIS jihadists who are exploiting security gaps between the Iraqi and Peshmerga forces.
