In December of 2015, 87 people were killed in response to a Burundian army base being attacked by gunmen.

Violence and resistance in Burundi increased after President Nkurunziza announced he would seek a third term. In efforts to silence opposition to his rule, more than 400 people have died and more than 240,000 have fled as refugees.

The rights group Amnesty International has found possible mass graves where the approximately 50 victims from the crackdown in December are likely to be buried.

Amnesty’s regional director for East Africa, the Horn and the Great Lakes, Muthoni Wanyeki, said the images are proof that there was a “deliberate effort by the authorities to cover up the extent of the killings by their security forces and to prevent the full truth from coming out.”

The recent violence in Burundi is planned to be addressed by African Union leaders at a summit in Ethiopia.