A homicide car bomber struck an armored vehicle carrying U.S. troops near the city's airport Thursday. The blast killed at least six Afghan civilians and wounded up to 20 others, officials said.

The Taliban claimed responsibility for the attack.

None of the four American troops traveling in a two-vehicle convoy were badly wounded, said Lt. Col. David Johnson, a spokesman for U.S. forces. The troops were traveling in one SUV and one truck, he said. Most U.S. vehicles are armored.

The homicide car bomb turned into a fiery hull that burned on the main airport road long after the attack.

Several other vehicles were damaged in the explosion.

Six Afghan civilians were killed and up to 20 others were wounded in the blast, Deputy Interior Minister Munir Mangal said. The attacker was driving a white Toyota Corolla, he said, a favorite among homicide car bombers.

In a mobile phone text message to an Associated Press reporter in Pakistan, Taliban spokesman Zabiullah Mujahid identified the homicide bomber as Abdullah.

U.S. troops and international security contractors surrounded the area after the blast.

Mohammad Salim, an eyewitness, took four wounded Afghans to the hospital.

"I saw the Americans getting out of the vehicle, then pointing their guns. Then they moved under a tree," Salim said.

Insurgents detonated 160 suicide attacks in 2007, a record number, the U.N. has said. Last year was the deadliest in the country since the 2001 U.S.-led invasion with more than 8,000 insurgency related deaths year, the U.N. said.