BAGHDAD - A suicide bomber driving an explosives-laden truck filled with sand struck a police station north of Baghdad yesterday, 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, after the driver told the guards he was delivering the sand to a construction site inside. The driver detonated his payload when two police officers 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 U.S.-Iraqi security crackdown and a groundswell of public opinion that has turned Sunni tribal leaders against the terrorist network.

U.S. troops killed 12 suspected al-Qaeda in Iraq fighters and detained 13 in a series of raids in central and northern Iraq, including one that ended with an air strike on a palm grove where gunmen had taken up positions outside Youssifiyah, 12 miles south of Baghdad, the U.S. military said.

The raids came days after an al-Qaeda front group, the Islamic State of Iraq, posted a message on an extremist Web site announcing a new campaign against members of so-called awakening groups, a corps of local citizens - some former insurgents - who have turned against the extremists and have been credited by the United States with helping to reduce violence nationwide.

Yesterday's attack in Beiji capped a deadly week in which nearly 80 people were killed and dozens wounded by roadside bombs, car bombs and suicide attacks, most targeting Iraqi security forces or anti-al-Qaeda groups north of Baghdad.

"This attack will not deter us and the bombings will not frighten us because we are serving our country and protecting out citizens," said Col. Hazim Jamil of the Beiji police force.

Police and witnesses said the bomber made it through the main gate by hiding his explosives under sand. He was stopped when he tried to drive his truck into a parking lot behind the police station. Guards had become suspicious because he was trying to enter an area that was not under construction.

Violence is generally down throughout Iraq, largely due to a U.S. troop buildup, the rise of the anti-al-Qaeda groups, and a freeze on activities by the Mahdi Army ordered by the militia's leader, the radical cleric Muqtada al-Sadr. But with the loss of many former sanctuaries, al-Qaeda groups are believed to be moving to more remote regions.

In the southeastern city of Kut, a rocket landed on the home of a senior member of the local Sadrist bloc of Shiite politicians, killing him, his wife, and their two children, police said.