A suicide bomber driving an explosives-laden truck filled with sand struck a police station north of Baghdad, the latest in a week of bombings that have killed nearly 80 people. The truck was allowed through the main gate of the complex in Beiji, the site of Iraq's largest refinery, on Saturday after the driver told the guards he was delivering the sand to a construction site inside. The driver detonated his payload when two policemen approached him as he tried to enter a parking lot, police said. The blast, which damaged nearby homes and sent shards of glass flying through the air, killed eight people and wounded 16, police said. It occurred in a neighborhood that is home to many refinery workers and engineers, but apparently was targeting the station. Violence has been unrelenting in northern Iraq as insurgents fight back against a US-Iraqi security crackdown and a groundswell of public opinion that has turned Sunni tribal leaders against the terror network.