KABUL, Afghanistan — A car bomb exploded near a three-vehicle U.S. Embassy convoy on a busy road in Kabul on Monday, wounding several people, one seriously, officials said.

The blast, witnessed by an Associated Press reporter, badly damaged the front of one black SUV that was shunted to the other side of the road. First aid was administered to at least two people at the scene.

The other two vehicles in convoy also were damaged, close to the burning wreckage of the car where the bomb was apparently planted.

Joe Mellott, a spokesman for the U.S. Embassy, said several people in the convoy were wounded, one seriously. He did not identify them or say whether they were Americans. He said the U.S. ambassador, Ronald Neumann, was not in the convoy.

An initial alert over an embassy warning system said, "a U.S. Embassy convoy was struck by a suicide bomber in the vicinity of the U.S. Embassy," according to an AP reporter who heard the alert over the phone.

Mellott said the warning was initial incoming information, and it wasn't immediately clear if it was a suicide bomber who carried out the attack.

The bombing took place about 2 miles from the embassy on a road often targeted in bombings and rocket attacks. The road leads out of Kabul and to the U.S. base at Bagram.

The AP reporter who witnessed the attack happened to be traveling in a vehicle about 50 to 70 yards behind the convoy when the bomb went off.

U.S. Embassy security teams initially prevented Afghan police, NATO soldiers and journalists from getting close to the vehicles.

Late last month, a suicide bomber killed 23 people outside the U.S. base at Bagram during a visit by U.S. Vice President Dick Cheney. In September, a suicide bombing near the U.S. Embassy killed 16 people, including two U.S. soldiers.

Afghanistan has seen an upsurge in Iraq-style violence over the past year as militant supporters of the former Taliban regime have stepped up attacks and increasingly embraced new deadly tactics such as suicide and roadside bombings.