Possible friendly fire leaves 5 US troops dead in Afghanistan

      KABUL, Afghanistan (AP) -- An apparent friendly fire incident has killed five Americans troops in southern Afghanistan.

      That's according to a U.S. defense official who would provide no other details. An Afghan official said it happened in southern Zabul province.

      A statement from NATO says the casualties happened during a "security operation" after the soldiers "came into contact with enemy sources." A senior police official said the coalition soldiers may have been killed when they called for close air support.

      If confirmed, it would be one of the worst cases of coalition-on-coalition friendly fire during the nearly 14 year war.

      In 2002, four Canadian soldiers were killed when an American F-16 jet fighter dropped a bomb on a group near a night firing exercise in southern Kandahar.