Two Americans were wounded as well, the official said.

The NATO-led force reported that three service members died in the bombing.

More than 1,900 Americans and another 1,000-plus allied troops have died in the 10-year conflict.

On Sunday, a NATO service member was shot to death by a gunman in an Afghan army uniform in southern Afghanistan, the allied command in Kabul reported.

The attacker was killed by coalition forces who returned fire, the NATO-led force reported.

The year has seen a number of attacks on coalition forces by Afghan forces or by insurgents who have disguised themselves as Afghan troops, fueling distrust at a critical period of the conflict.

In another attack Sunday, a roadside bomb struck a vehicle carrying U.S. troops in eastern Afghanistan, killing one American and wounding two, a Western official said. The bombing happened about 10 kilometers (6 miles) south of an outpost in Paktia province, near the Pakistani border, the official said.