U.S. soldiers arrested nearly 50 people and confiscated weapons in several raids in Iraq's volatile Sunni Triangle (search) after a series of bombings that killed six U.S. soldiers.

A U.S. soldier died Sunday of wounds suffered in a grenade attack on his Bradley vehicle that was patrolling a central Iraqi town of Beiji (search) the day before, said Maj. Josslyn Aberle, a spokeswoman for the 4th Infantry Division.

Five other U.S. soldiers were killed in separate bombings and a blast that narrowly missed an American convoy killed four Iraqis and wounded about 40 others in a bloody day of attacks on Saturday.

The deaths raised to 513 the number of U.S. service members who have died since the United States and its allies launched the Iraq war March 20. Most of the deaths have occurred since President Bush declared an end to active combat May 1.

The violence underscores continued resistance to the American occupation that is strongest in the Sunni heartland north and west of Baghdad (search), despite the Dec. 13 capture of Saddam Hussein (search).

On Sunday, U.S. soldiers raided several locations in Baqouba, 35 miles northeast of the capital, and captured 46 people including three men suspected of involvement in anti-coalition activities, Aberle said. The remaining 43 were detained for possessing weapons without authorization, she said.

In Mukayshifa, a town south of Tikrit (search), soldiers raided a house Saturday and confiscated 220 hand grenades, Aberle said.

Insurgents fired the rocket propelled grenade at the Bradley in the town of Beiji, north of Tikrit, late Saturday, piercing the driver's compartment and critically wounding the soldier. The soldier was evacuated to a military hospital, where he died.

A second Bradley fighting vehicle returned fire toward the area from where the grenade was launched, and soldiers later captured six men who were in the possession of a grenade launcher, Aberle said.

In Khaldiyah, some 70 miles west of Baghdad, three U.S. soldiers were killed and six more were wounded Saturday when a vehicle, possibly driven by a suicide bomber, exploded at a U.S. checkpoint near a bridge across the Euphrates river, the U.S. command said.

Iraqi witnesses said a four-wheel-drive vehicle drove up to the checkpoint and exploded in front of a U.S. Army Humvee trying to block it. At least eight Iraqis — six of them women — were injured, according to Dr. Ahmed Nasrat Jabouri of the provincial hospital in nearby Ramadi.

Two other U.S. soldiers were killed by a roadside bomb that struck their four-vehicle convoy north of Fallujah, a Sunni Muslim city near Khaldiyah in a center of anti-American resistance.

A fourth attack took place when a truck bomb exploded Saturday morning near government buildings in Samarra, about 70 miles north of Baghdad, barely missing a U.S. military police patrol as it turned into a police station compound.

The blast killed four Iraqi civilians and wounded about 40 people, including seven American soldiers who were cut by flying glass inside one of the buildings. The Americans' wounds were not life-threatening.

The explosion set fire to a half-dozen cars parked near the buildings, which included a police station and municipal offices, and gouged a large crater in the street. The burned-out hulks of the cars — some reduced to mounds of twisted metal — smoldered in the damp, chilly air hours after the blast.

In other developments Sunday:

— The police chief of Tathrib town was arrested following allegations of corruption. Soldiers from the 1st Squadran, 10th Cavalry Regiment searched his house Saturday and confiscated five AK-47 rifles, two other rifles and ammunition. No details of the corruption allegations were, however, known, Aberle said.

— A roadside bomb exploded near a U.S. patrol in the Iraqi capital, Baghdad, but no injuries were reported, a U.S. soldier said, speaking on condition of anonymity.