In the shooting near the Baghdad airport, the American military disputed the Interior Ministry’s account and described the three people who were killed as “criminals” who had fired on the convoy.

Elsewhere in Iraq, a car bomb in Salahuddin Province on Sunday killed seven policemen, and in Diyala Province the police shot a female suicide bomber.

The car bomb exploded in Dhuluiya, a town 45 miles north of Baghdad that has been the scene of fighting between the Iraqi security forces and the Islamic State of Iraq, one of the most extremist Sunni insurgent groups.

The police had been in a nearby rural area of farms and orchards conducting an operation. As they finished, they saw the vehicle, a small pickup truck, parked by the side of the road, said Maj. Maahadi Al-Jubori of the Dhuluiya police.

One of the policemen called the district commander before approaching the truck. The commander told him not to go forward, according to another policeman who was there. But the policeman and several colleagues approached it anyway. Moments later the bomb exploded.

Six people died at the scene, a seventh died on his way to the hospital and three others were severely injured.

In the Diyala shooting, police officers saw a woman walking toward security barriers near the town council building in Wajihiya district, a few miles north of the provincial capital, Baquba. They shouted at her to stop, but she continued walking. Fearing she was a suicide bomber, the police shot her. The bomb she was carrying detonated, about 40 feet before she reached the barriers, said a police official in Baquba. A civilian was badly wounded by the blast.

In Diwaniya Province in southern Iraq, American military officials on Monday will hand over control of security to Iraqi forces, said Hussein al-Budayiri, a provincial council member.

Diwaniya will be the 10th province to be transferred to Iraqi control, joining Muthanna, Karbala, Najaf, Dhi Qar, Maysan, Basra, Dahuk, Erbil and Sulaimaniya. All of the provinces that have been transferred are either in Kurdistan, to the north, or in southern of Iraq.

The intelligence commander for Basra, Brigadier Jabar Mujhed, was assassinated by gunmen while visiting Baghdad on Saturday, according to an Interior Ministry official, who asked not to be identified since he was not authorized to talk to the press.