Local police chief Marlon Rajagukguk told AFP of the incident: "The cliff surrounding the mine collapsed and buried twelve women, killing them all." He added that the victims, aged between 30 and 55, were not professional miners.
The police chief said that rescuers needed hours to evacuate the bodies of the victims because they were in a 2-meter deep hole filled with mud. "Now, all the bodies of the victims have been returned to their families," he said.
Rescuers saved two injured women from the rubble after two hours of search and rescue.
It is common in all unlicensed mines in mineral-rich Indonesia. Abandoned deposits in the region attract locals searching for gold tailings while not using the appropriate safety equipment.
Illegal mining is common in Indonesia; many people in the country try to make a living by working in unpredictable conditions. The Mandailing Natal district, located about 300 km south of the provincial capital Medan, has several sites that are not in operation after being abandoned by operators.
Landslides, flooding, and collapses of tunnels or other structures have been recurrent. There are frequent mining accidents all over the region, occurring mainly during the monsoon summer months.