A truck bomber plowed through a sandbag barrier to strike a police station in the northern Iraqi city of Mosul on Tuesday, killing at least eight people and wounding 12, U.S. and Iraqi officials said.

The bomber in Mosul broke through the first checkpoint on the station's perimeter, which was made of sandbags, then detonated his explosives when he reached the concrete wall a few yards away from the building, according to local police.

The attack occurred about 6:30 a.m. at the Mahta police station in central Mosul, police Maj. Jassim al-Jubouri said.

The U.S. military confirmed the attack, saying at least four Iraqi police officers and four civilians were killed while three Iraqi policemen and nine civilians were wounded.

However, Maj. Derrick Cheng, a spokesman for American forces in northern Iraq, said the truck bomber detonated his explosives after Iraqi police began firing at the truck when it took a sharp turn toward a train terminal.

Nobody claimed responsibility for the attack. But vehicle bombings are the signature attacks of suspected Sunni insurgents who remain active in Mosul, 225 miles northwest of Baghdad.

The British military, meanwhile, transferred over coalition command of the oil-rich southern province of Basra to the United States on Tuesday. It was the latest step toward the withdrawal of the remaining 4,100 British troops from Iraq by midsummer.

The British troops will be withdrawn in phases, with combat operations due to end at the end of May and all but about 400 troops withdrawn by the end of July. Those staying behind will be involved in training Iraqis, according to the British Ministry of Defense.

"As the Iraq people continue to stand on their own, we will support them and we will stand together shoulder-to-shoulder united against our common enemies and committed to peace and prosperity," the top U.S. commander in Iraq, Gen. Ray Odierno, said at a ceremony to mark the Basra handover.

Britain, which had been a staunch U.S. ally since the March 2003 invasion, handed over security responsibilities in Basra to the Iraqis late last year but continued to maintain its presence on a base at the airport outside the city.

Iraq's deputy chief of staff for armed forces Lt. Gen. Naseer al-Ebadi thanked the British forces for training and equipping the Iraqis and said his forces were ready to take over.

"Iraqi security forces are capable of maintaining order and security," he said.

The No. 2 U.S. military commander in Iraq, Lt. Gen. Lloyd Austin, acknowledged earlier this month that problems in Mosul "can put us off track and cause violence to really re-ignite in a greater way."

Tuesday's bombing is the latest in a string of attacks in Iraq this month that has raised fears insurgents are trying to regroup as the U.S. prepares to leave Iraqi cities in three months and the entire country by the end of 2011.

U.S. forces have been handing over responsibility for American installations in preparation for the withdrawal. On Tuesday, it transferred control of one of its largest bases in Baghdad — Forward Operating Base Rustamiyah.

The base was heavily rocketed during fierce fighting before violence ebbed about 18 months ago.