Afghan police were investigating at the scene and the area police chief said he was deeply disturbed by the incident.
Separately, Nato-led forces killed 38 Taliban fighters in two attacks in southern Afghanistan on Thursday, a provincial police official said.

Backed by air support, the attacks targeted hideouts in two areas in Helmand province, the main drug producing region of Afghanistan, the world's leading producer of heroin, the district police chief said.
He said 11 Taliban fighters were killed in one attack and 27 in another, adding that there were no casualties among Nato or Afghan troops.