U.S. warplanes struck targets in central Iraq on Sunday, witnesses reported, and at least three people were wounded when mortar shells hit an oil company compound in the northern city of Kirkuk (search), officials said.

Jets bombed areas around the city of Samara, about 75 miles north of Baghdad, according to the witnesses. The U.S. military did not immediately confirm the strikes.

Coalition aircraft and artillery have targeted suspected rebel areas for the past two weeks as part of their offensive against guerrillas in central and northern Iraq.

In Kirkuk, 150 miles north of Baghdad, the manager of the Iraqi Northern Oil Company (search) said a club inside the company compound was struck overnight by mortar shells and that three foreigners were hurt.

Adel Al-Qazzaz (search) said he did not know the nationality of the wounded or whether they are soldiers or civilians.

U.S. officials have warned of even more attacks as the Islamic holy month of Ramadan nears its end Tuesday.

On Saturday, insurgents hit a civilian cargo plane with a surface-to-air missile, but the aircraft landed safely.

The plane, operated by the Belgium-based cargo service DHL, was the first civilian airliner to be hit by insurgents, who have shot down several military helicopters with shoulder-fired rockets. DHL and Royal Jordanian, the only commercial carrier flying into Baghdad, immediately suspended flights.

The U.S. occupation authority said it was investigating the cause, but a military official said on condition of anonymity that a SAM-7 surface-to-air missile struck the plane. The damage to the plane also appeared consistent with the effects of a missile hit.

Also Saturday, suicide bombers struck two police stations northeast of Baghdad within 30 minutes. In the market town of Khan Bani Saad, a Chevrolet Caprice sped through a guard's gunfire Saturday morning and exploded at the station gate, police said.

The U.S. military said 10 people were killed: six policemen, three civilians and the driver. Iraqi police said one of the dead was a 5-year-old girl. Another 10 people were wounded.

In Baqouba, 12 miles to the northeast, a white SUV approached the gate to a police station at normal speed but ignored orders to stop and then blew up at the checkpoint, witnesses said.

Three policemen and the driver were killed, and one policeman was missing, the Iraqi police said. At least 10 civilians were hurt.

Elsewhere, an Iraqi police colonel in charge of protecting oil installations was assassinated in northern Iraq, part of what appeared to be an insurgent campaign against U.S.-backed security forces.

Col. Abdul-Salam Qanbar, who was in charge of a police force in the northern city of Mosul, was fatally shot Saturday evening while heading to a mosque, a spokesman said.

"It is clear that the terrorists have targeted Iraqis, the very Iraqis who are trying to improve the security in Iraq and the lives of ordinary Iraqis," coalition spokesman Charles Heatly said.

Also Saturday, a remotely detonated bomb hidden in a juice cart exploded near an American convoy in the northern city of Mosul, police and witnesses said.

No Americans were injured, but two Iraqis were hurt when, according to police, U.S. soldiers stunned by the explosion opened fire in all directions. The U.S. military said it was investigating.