An Afghan policeman conducting a joint operation with US soldiers opened fire on the Americans, killing two of them before fleeing, an Afghan official said Saturday.
The US military earlier said two American troops died in a firefight in Wardak on Friday, but declined to confirm any new details.
Shahidullah Shahid, a spokesman for the Wardak provincial governor, said the policeman fired on the Americans while they were patrolling together Friday night, killing two and injuring two. Shahid said two of the officer's relatives were in custody for questioning.
A third US service member died Friday of wounds from a bomb attack in Wardak the day before.