(KUNA) -- Three Iraqi policemen from a unit assigned to protect oil facilities in northern Iraq were injured on Tuesday. A security source said the three men were injured when a bomb exploded as their patrol passed by in an area north of Kirkuk.Seperately, one of kirkuk's village chiefs was assassinated in his car by unidentified gunmen. In Kirkuk also, ceremonies were taking place at the Kiwan military base, on the occasion of the coalition forces' handing over the authority to the Iraqi army. A large number of senior officials attended the event. "The Iraqi army now is able to take over due to the continuous support it received from the Multi-National forces in the earlier stages," deputy of the denfense ministry said. Kiwan military base provides backup to the military units through the management and logistic support especially to the units stationed in Kirkuk.