The first car bomb exploded in front of a Baqubah police station early Saturday.

Witnesses say the driver of the vehicle raised little suspicion as he approached the police station's gate and detonated his explosives. The blast killed and injured more than a dozen policemen and civilians. Minutes later, a suicide bomber sped his car toward a police station in the town of Khan Bani Saad, 20 kilometers south of Baqubah. Witnesses there say he blew up the vehicle as Iraqi police opened fire. The U.S. military says more than a dozen policemen and civilians were killed and wounded in that attack.

Since Wednesday, there have been at least five car bombings in Iraq, targeting Iraqis who work with the U.S.-led coalition. On Wednesday, a car bomb exploded outside the home of a pro-coalition tribal leader in Ramadi in central Iraq. A day later, a suicide car bomber struck the offices of a Kurdish political party allied with the United States, in the northern city of Kirkuk.

Baqubah and Khan Bani Saad both are part of the "Sunni Triangle," north and west of Baghdad, where anti-coalition resistance has been fierce for months.

Meanwhile, an Airbus cargo plane made an emergency landing at Baghdad International Airport Saturday, with its left wing on fire.

A spokesman for the Coalition Provisional Authority, Charles Heatley, says the plane had departed the airport for Bahrain when the fire forced the plane to turn around. He says it is not yet known what caused the blaze.

"As far as we know, there was some damage to one of the engines. It is not entirely clear exactly what that was caused from, until the investigation is complete," he said.

Residents around the airport report seeing smoke trails heading toward the airplane, leading some officials here to believe that the plane may have been hit by a surface-to-air missile.

If so, it would be the first time a fixed-wing aircraft has been hit by a missile in Iraq.