The attack follows another similar incident earlier this month that took place in the same Metakal zone of Ethiopia's Benishangul-Gumuz region, which borders Sudan, where 30 people were killed.
"Civilians are being subjected to repeated attacks with unmitigated cruelty in Benishangul-Gumuz," said Daniel Bekele, the head of the EHRC. "Federal and regional authorities should take the required steps to enforce the rule of law and bring perpetrators to account."
The Commission did not say what was behind the attacks and Abera Bayeta, the region's peace and security head, did not immediately respond to calls seeking comment.
The Commission said that the Ethiopian National Defense forces engaged in a shootout with armed gunmen in the area and were able to restore calm by Friday afternoon.The killing is the latest incident of violence in the region. In June last year, men in camouflage uniforms killed more than 50 people and injured 23 in the same area.