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A bomb-laden car plowed through a razor wire fence and exploded outside a police station in the north of the country Saturday, killing nine Iraqis and injuring 45, including policemen there to pick up their pay.

Hours later, a mortar attack hit a Baghdad neighborhood, killing five people and wounding four.

In a separate incident, three U.S. soldiers from the 4th Infantry Division (search) were killed Saturday in a roadside bombing near the northern oil center of Kirkuk. Their deaths brought to 522 the number of American service members who have died since the Iraq war began March 20.

It was unclear if the attack on the police station in Mosul was a suicide bombing or the driver fled before the explosion. U.S. officials have said recent vehicle bombings and suicide attacks in Iraq bear the mark of Al Qaeda (search).

The mortar was fired Saturday night into Baghdad's residential area of Baladiyaat (search), a predominantly Palestinian immigrant area. The projectile gouged a crater and sent shrapnel flying all around, killing four Palestinian residents, neighbors and relatives said. The fifth victim was an Iraqi who was visiting the area, they said.

On Sunday, residents carried the bodies of the four Palestinians in coffins draped in Palestinian flags from a mosque to their homes before taking them to a cemetery for burial. Some young men in the funeral procession fired rifles in the air, a traditional gesture by Arab while mourning as well as celebrating.

A series of strong explosions could be heard in the center of Baghdad over a period of about two hours Saturday night. It was unclear what caused the blasts, some of which were accompanied by bursts of automatic weapons fire.

A U.S. military spokesman, Capt. Dave Malakoff, said one of the blasts occurred in Baladiyat, but he had no further details.

The fatal attacks were part of a series of violent incidents Saturday on the eve of the four-day Eid al-Adha, or Feast of Sacrifice. The feast, a major Muslim holiday, commemorates the Quran's account of God allowing the patriarch Abraham to sacrifice a sheep instead of his son Ismail. The Old Testament account says another son, Isaac, was spared.

Brig. Gen. Mark Kimmitt, deputy chief of staff for operations, told reporters Friday that coalition forces were prepared to deal with any surge in violence during a coming holiday. The start of the Islamic holy month of Ramadan last year was accompanied by a sharp escalation in insurgent attacks.

Repeated attacks by insurgents on police, politicians and other Iraqis who work with the U.S.-led coalition have been increasing in an apparent attempt to undermine support for the U.S. occupation authority and frighten the population into avoiding contact with the foreign administration.

Policeman Bassil Shehab, who suffered extensive facial burns and shrapnel injuries in the Mosul bombing, called the attack a "criminal act to kill innocent people. They have no religion, and no faith," he said of the attackers. "Nothing will stop me from going back to work even if something worse happens."

Also Saturday, a bomb exploded under the car of police Col. Adnan Radeef al-Ani in front of his house in Baghdad, slightly injuring five children in the street. Al-Ani told The Associated Press the bomb apparently was triggered by a timer but no one was in the vehicle when it exploded.

In the southern Iraqi city of Basra, a remote-controlled bomb hit a car belonging to a Danish relief organization Danchurchaid on Saturday, wounding two aid workers and several Iraqis, according to the Danish group and military officials said.

A number of humanitarian groups withdrew their international staff after deadly bombings against the headquarters of the International Committee of the Red Cross and the United Nations in Baghdad last year.

Witnesses to the attack on the police station in Mosul, 225 miles north of Baghdad, said what appeared to be a suicide attacker drove through a security barricade in front of the police station before blowing up his vehicle. Iraqi officials confirmed a car bomb but were unsure if the driver detonated the explosive from inside or parked and fled.

Saturday was a pay day and the station was crowded with staff at the time of the midmorning bombing, said police Lt. Mohammed Fadil. Five of the dead were police and the others were Iraqi civilians, policeman Khalid Ahmed said.

Severed limbs, some of them smoldering, and decapitated bodies littered the bloodied street after the attack, the sixth major vehicle bombing in Iraq in the past two weeks but the first in Mosul, the country's third-largest city and the principal metropolis in the north.

The blast gouged a huge crater in the street and shattered windows of nearby buildings. Pieces of burning car wreckage spewed acrid, black smoke. At least five cars were destroyed.

Stunned survivors stumbled down the street, their clothing soaked in blood. American soldiers in full combat gear hurried to the scene and cordoned the area. No U.S. troops were near at the time of the blast.

"I fell to the ground and hit my head," said Lt. Ahmed Abdul Kader, 30, who was inside the police station. "I couldn't get up. There were people with horrible injuries all around me."

Policeman Bassil Shehab, who suffered extensive facial burns and shrapnel injuries, called the attack a "criminal act to kill innocent people. They have no religion, and no faith," he said of the attackers. "Nothing will stop me from going back to work even if something worse happens."

Police stations have been the frequent targets of insurgents fighting U.S. troops and their Iraqi allies since the fall of Saddam Hussein's regime last April. Many of the attacks have been carried out with car bombings and roadside bombs that have killed scores of civilians.

In the deadliest insurgent attack since the capture of Saddam on Dec. 13, a suicide car bombing Jan. 18 at the gates of the U.S.-led coalition headquarters in Baghdad left at least 31 people dead and more than 120 injured.

Four people, including a South African, died Wednesday when a suicide driver in a van disguised as an ambulance blew up his vehicle in front of a Baghdad hotel frequented by Westerners.

U.S. officials have pointed to the rash of vehicle bombings as evidence that Usama bin Laden's terrorist network may be trying to gain a foothold in Iraq. Although most attacks are believed carried out by Saddam loyalists, suspicion of Al Qaeda involvement has risen with the arrest this month of a top Al Qaeda operative, Hassan Ghul, who was captured by U.S.-allied Kurdish fighters as he tried to enter the country from Iran.