A checkpoint shooting in eastern Afghanistan has taken the U.S. military's death toll in the 11-year-old conflict past 2,000.
The NATO-led international mission, ISAF, said a U.S. soldier, a civilian contractor, and three Afghan troops died in an exchange of fire late Saturday in Wardak Province.
The mission initially said the American soldier was believed to have been killed by a member of the Afghan security forces, but deputy ISAF commander Lieutenent General Adrian Bradshaw later told journalists that "insurgent fire" may have been involved in the incident.
The shooting is now under investigation by a joint Afghan and coalition team.
At least 52 members of the NATO-led force have been killed this year in "insider" attacks in which members of Afghan security forces turn their weapons on their Western allies.
Based on reporting by AFP and BBC