BAGHDAD — Suspected Sunni insurgents ambushed a minibus carrying Iraqi police recruits near the Syrian border yesterday, killing all 11 passengers, Iraqi officials said — the first deadly attack since Iraqi forces launched a major sweep against Al Qaeda fighters in the region.

The hail of gunfire came hours after Iraqi officials said they arrested a man suspected of being Al Qaeda in Iraq’s chief leader in the northern city of Mosul, the terror network’s most prominent urban stronghold.

The attack, the bloodiest in months against police, left the minibus riddled with bullets in the desert west of Mosul. Some Al Qaeda fighters are believed to have fled the city toward neighboring Syria.

Police discovered the bodies of the police recruits and their minibus near Baaj, a remote town 20 miles from the Syrian border, according to a provincial official in Baaj and a Mosul police officer. The policemen, most from Baaj, were returning from their recruitment camp, they said.

It appeared a large group of insurgents had ambushed the minibus with a spray of gunfire. Nine bodies, including the police driver’s, were found still in the vehicle and two on the ground outside, the two officials said. They spoke on condition of anonymity because they were not authorized to talk to the press.

The provincial official said the attack had the hallmarks of Al Qaeda in Iraq and could have been in retaliation for the Mosul crackdown, launched more than a week ago. The U.S. military said it was looking into reports of the attack.

Until now, the Mosul sweep had seen almost no violence, even as American-backed Iraqi soldiers and police conducted arrest raids in the city — a sign that militants had fled. Yesterday, the Defense Ministry announced the first death in the crackdown, a militant killed in Mosul.