Two car bomb attacks on the highway to Baghdad's (search) international airport killed two American soldiers and wounded 11 on Saturday, the military said.

The first bomb exploded near an overpass on the road linking the capital to the airport as a convoy passed by, wounding three soldiers. Plumes of thick black smoke were seen rising from the scene and a U.S. helicopters clattered overhead.

At around 4 p.m., U.S. soldiers traveling to the scene of the attack were hit by a second car bomb, killing two and wounding 11, the military said.

The treacherous stretch of road is the site of frequent attacks against U.S. troops and their supply convoys.

In a travel warning issued Saturday, the U.S. State Department (searchdescribed the airport road as among the country's most dangerous.