Washington ? Two contractors working for the CIA were killed in an ambush in Afghanistan, the agency said Tuesday.

William Carlson, 43, of Southern Pines, N.C., and Christopher Glenn Mueller, 32, of San Diego, were “tracking terrorists operating in the region” of Shkin, a village in eastern Afghanistan, when they were killed Saturday, the CIA said in a statement.

Both were veterans of military special operations forces, the CIA said.

“William Carlson and Christopher Mueller were defined by dedication and courage,” CIA Director George Tenet said in a statement. “Their sacrifice for the peoples of the United States and Afghanistan must never be forgotten.”

The pair was working for the CIA’s Directorate of Operations, which conducts covert operations.

The CIA statement said the agency consulted with the dead officers’ families and decided their names could be released without compromising ongoing operations.

They are the third and fourth CIA operatives that the agency has acknowledged have been killed in the line of duty since the Sept. 11 attacks.

The first, paramilitary officer Johnny Micheal Spann, was killed during an uprising of Taliban and al-Qaida prisoners in northern Afghanistan on Nov. 25, 2001.

The second, Helge Boes, died in a training accident in eastern Afghanistan, on Feb. 5, 2003.

The region Carlson and Mueller were operating in is part of the remote mountainous region along the border of Afghanistan and Pakistan, where Osama bin Laden is thought to be hiding. It is also a stronghold for al-Qaida, Taliban and other anti-U.S. fighters.