Baghdad ? A bomb in a parked car struck worshippers heading to a Shiite mosque Sunday in Baghdad, killing at least nine people as Iraqis celebrated a Muslim holiday, while the death toll rose to 18 in a coordinated suicide truck bombing and ambush north of the capital.

Relatives and rescue workers pulled bodies from under piles of concrete bricks and rubble in the Sunni city of Samarra, where a suicide truck bomber detonated his explosives late Saturday. Guards had opened fire before he could reach the targeted police headquarters.

Gunmen drove up and fought with police immediately after the blast, which tore through nearby buildings. At least 18 people were killed and 27 wounded, police said.

Nobody claimed responsibility for the attacks in Baghdad and Samarra, but they bore the hallmarks of al-Qaida in Iraq militants who had promised an offensive during 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 ended this weekend with the three-day Eid al-Fitr festival that began on Friday for Sunnis and Saturday for Shiites.