A mother and her four children were killed in Dhagax Madow, Somali region in Ethiopia on Tuesday after an object suspected to be ordnance exploded.
According to the residents who spoke to BBC Somali service, the blast which also injured four other people took place on Monday evening.
A relative of the victims who also confirmed the incident said the family was using a metal liked object as a crushing tool ( pestle) when the explosion occurred.
The device which is believed to be a remnant of 1977 Somali-Ethiopia war has been used by the family of seven unknowingly before it exploded killing five of them.
The father and a child survived.
Somalia and Ethiopia fought from July 1977 and March 1978 over the disputed Ethiopian region of Ogaden.
The mines used during the war by both sides still believed to be in the area once occupied by the Somali military before international community intervention in favor of Ethiopia.