Yahya Ahmed, Associated Press
Yasir Nawaf, 18, who was wounded in a suicide car bomb attack that struck a group of police recruits in the town of Jalula, arrives for treatment at a hospital in the northern town of Sulaimaniyah, where some of the 40 wounded had been taken.

BAGHDAD — A suicide bomber with explosives hidden beneath his traditional robe blew himself up Tuesday in a crowd of Iraqis trying to join the police force, killing at least 25 people in the second major bombing in Iraq this week.

The attack occurred in the town of Jalula, a remote, impoverished community about 80 miles northeast of Baghdad that lies in Diyala province, where a U.S.-Iraqi offensive is being waged against the last major insurgent stronghold near the capital.

The bomber mingled in the crowd of would-be police recruits and then detonated explosives hidden beneath his dishdasha robe, police said. The bomb was packed with nails and ball bearings to maximize casualties, police said.

Initial reports from police and the U.S. military said the bomber blew up an explosives-laden vehicle near the crowd, but authorities said later that officers first concluded erroneously that a parked car damaged by the blast had been used as a car bomb.

U.S. military officials said five policemen were among the dead.

Police guard Falah Hassan, 28, said he was standing at the gate of the Jalula police compound when he heard a thunderous explosion about 100 yards away and was hit by debris.

"I saw burned bodies, wounded people and small pools of blood," said Hassan, speaking from a hospital bed in Sulaimaniyah where some of the 40 wounded were taken.

The local police chief, Col. Ahmed Mahmoud Khalifa, said jobs in the police force are prized in Jalula, a mostly Sunni Arab town of 67,000 people with a substantial Kurdish population, because unemployment is high.

He said tribal sheiks had been asked to send recruits for a new police emergency response unit, and applicants came to the police center Tuesday to check whether they had been accepted.

"Today I was so happy to get a job at last to feed my wife and two kids," said Yasir Ramadan, 21, an applicant who was wounded by shrapnel and will need eye surgery. "I used to work as a day laborer in construction. But there's no construction in the area, and it's hard to find work."

No group claimed responsibility for the bombing, but suicide attacks are the hallmark of al-Qaida in Iraq and other Sunni Islamist extremists that operate in Diyala, which is among the most violent areas in the country.

On Sunday, a suicide bomber blew himself up among well-wishers welcoming home an Iraqi detainee released from U.S. custody, killing at least 25 people on the western outskirts of the Iraqi capital. The victims included members of a U.S.-backed Sunni volunteer force raised to fight al-Qaida.

Militants often attack police stations and recruiting drives trying to disrupt U.S.-led efforts to build up local security forces and undermine support for the insurgency.

Nevertheless, several wounded applicants, who were taken to a hospital in the Kurdish city of Sulaimaniyah, said they would not be deterred by the attack.

"We will beat terrorism and al-Qaida," said Yasir al-Dulaimi, 18, whose head and right arm were injured. "We will not abandon our work. If we do so, we will abandon our honor as well because al-Qaida would take full control over our area."

Elsewhere in Diyala, a roadside bomb killed five members of a Sunni family traveling Tuesday from Mandali on the Iranian border to visit a religious shrine. The dead included two women and two children, Col. Sarchal Abdul-Karim said.

Also Tuesday, a bomb planted in a parked car blew up in the city of Tikrit, 80 miles north of Baghdad. A police official initially said four people were killed, but later reports listed only 12 wounded.

Tikrit was the late Saddam Hussein's hometown and had been a hotbed of the Sunni insurgency since the 2003 ouster of the Iraqi leader. But it has enjoyed relative quiet since violence significantly dropped over the past year in much of Iraq.