An Afghan official says a policeman conducting a joint operation with US soldiers opened fire on the Americans, killing two of them.
The US military said two American troops were killed in a firefight in Wardak on Friday, but provided no other details. A third US service member died on Friday of wounds from a bomb attack in Wardak the day before.
Shahidullah Shahid, spokesman for the Wardak provincial governor, said on Saturday the policeman fired on the Americans, killing two and injuring two before escaping. He did not give a reason for the shooting.
Shahid says two of the policeman's relatives are in custody for questioning.