The deaths in Yemen of six suspected al-Qaida terrorists, including a key planner in the bloody attack on a American destroyer two years ago, appear to be the work of a missile fired by a unmanned U.S. aircraft.

Officials at the Central Intelligence Agency are not commenting on the incident, in which several al-Qaida members traveling in a vehicle were killed.

But a senior administration source, speaking on condition of anonymity, says the attack Sunday, appears to be the work of a Hellfire missile fired by a CIA controlled Predator unmanned drone aircraft. The CIA has used armed Predators before in Afghanistan.

Among those reported killed is Ali Qaed Senyan al-Harethi, a key suspect in the October attack two years ago in Yemen on the U.S. destroyer Cole. Defense Secretary Donald Rumsfeld says his death is good thing.

"Needless to say he has been an individual that has been sought after as an al-Qaida member as well as a suspected terrorist connected to the USS Cole so it would be a very good thing if he were out of business."

Seventeen U.S. sailors died in the attack on the Cole, which was struck by suicide bombers during a brief refueling stop in the Yemeni harbor of Aden.