A parked car bomb struck worshippers heading to a Shiite mosque Sunday in Baghdad, killing at least nine people as Iraqis celebrated a Muslim holiday. Authorities said 18 others died the day before when a suicide truck bomber followed by a swarm of gunmen attacked a regional police station.

Nobody claimed responsibility for the attacks, but they bore the hallmarks of al-Qaida in Iraq insurgents who had promised an offensive during the Islamic holy month of Ramadan to undermine U.S.-Iraqi claims of success in quelling the violence in the capital with an 8-month-old security operation.

The fasting month culminated this weekend with the three-day Eid al-Fitr festival that began on Friday for Sunnis and Saturday for Shiites.

After the bombing in Baghdad, police banned cars from the area surrounding the shrine in the Kazimiyah district in northwestern Baghdad until further notice, a police officer said. The twisted wreckage of the minibus was strewn across the road and nearly a block was blackened by the blast, according to AP Television News footage.

Earlier Sunday, police found a parked booby-trapped minibus in the same area — home to Baghdad's holiest Shiite shrine — but were able to detonate it without casualties, added the officer, who spoke on condition of anonymity as he was not authorized to release the information.

In other violence in Iraq, an Iraqi soldier was killed Sunday and four others were wounded when a roadside bomb targeted their patrol in Khan Bani Saad, just northeast of Baghdad in the volatile Diyala province. Near the southern town of Hilla, a police officer was fatally shot by gunmen from a speeding car.

Also Sunday, police raised the casualty toll from a suicide truck bombing a day earlier in the northern city of Samarra, 95 kilometers (60 miles) north of Baghdad. Police fatally shot a suicide bomber Saturday but his explosives-laden fuel tanker blew up near Samarra's police headquarters, killing 18 and wounding 27 others.

Immediately after the blast, about 20 vehicles with at least 60 gunmen drove up to the site and fought with police, said the official, speaking on condition of anonymity because he was not authorized to talk to media.

At least three police officers were wounded in the ensuing fighting, which ended after U.S. military helicopters flew overhead.

Dozens gathered amid the destruction to collect bodies and tend to the wounded, according to APTN footage.

An adolescent boy lay in a hospital bed, wearing a filthy T-shirt with half his face bandaged, said five members of his family were killed when the truck exploded near his home. Only he and his father survived, he said.

An American military official in the area said the gunmen were armed with rocket-propelled grenades and other weapons. The official credited Iraqi police with preventing further casualties.

Although no one claimed responsibility for the attacks Sunday and Saturday, they bore the hallmarks of the al-Qaida terror network.

Samarra lies in the heartland of the Sunni-led al-Qaida insurgency in Iraq and was the scene of the Feb. 2006 bombing that destroyed the golden dome of a famous Shiite shrine there. That bombing set in motion relentless bloodletting along the sectarian fault line that has threatened to divide the country.

In Haswah, about 50 kilometers (30 miles) south of Baghdad, a dozen insurgents were captured, including a man believed responsible for multiple attacks against U.S. and Iraqi forces and local residents, the U.S. military said, adding it was acting on tips. The men were cornered in a mosque where two AK-47s, two grenades, and two ammunition vests also were found, according to the military.

Meanwhile, Pope Benedict XVI made a public appeal in Rome on Sunday for the release of two Catholic priests kidnapped a day earlier on their way home from a funeral in northern Iraq.

Gunmen ambushed the priests' car, dragged them out and took them away, Archbishop Basile Georges Casmoussa, Mosul's head of the Syrian Catholic Church, one of the branches of the Roman Catholic Church.

Casmoussa himself was kidnapped in January 2005 and released a day later without ransom after the abductors realized his identity.

The pope asked the kidnappers to "let the two religious men go" during his traditional Sunday blessing to pilgrims and tourists gathered in St. Peter's Square.

The Christian community in Iraq is about 3 percent of the country's 26 million people.

In Saddam-era Iraq, the country's estimated 800,000 Christians were generally left alone, but after U.S. forces toppled the regime and sectarian clashes broke out, their situation grew more precarious.

In the summer of 2004, insurgents launched a coordinated bombing campaign against Baghdad churches. A second wave of anti-Christian attacks hit in September 2006 after Benedict made comments perceived to be anti-Muslim. Church bombings spiked and a priest, also in Mosul, was kidnapped and later found beheaded.

Many churches are now nearly empty, with their faithful either gone or too scared to attend.