A suicide bomber struck a bus Tuesday outside the city of Mosul, killing nine people and wounding three, the Iraqi army said. The bus, loaded with about 45 passengers, was heading to Syria from Mosul when the explosion occurred, about 60 kilometers (38 miles) west of the city, said an army officer, who spoke on condition of anonymity because he wasn't authorized to release the information. According to a preliminary report, the army said that the suicide bomber ordered the bus driver to take a route away from the highway to dodge army check points. The driver refused and the bomber blew himself up when the bus was about 500 meters from an army check point. Mosul has been billed by the US military as the last major urban stronghold of al-Qaida in Iraq and is a major focus of combined US-Iraqi efforts to drive out extremists whose influence has already been slashed in Baghdad.