The Kasai crisis began over a year ago when the government of Congo refused Jean-Pierre Mpandi, known as Kamuina Nsapu, the official status to the region’s traditional chiefs.

Mpandi then mobilized his militia in an uprising against the state. After he was killed in August 2016, the violence escalated. And over 3,000 people have been recorded dead, nearly 1.3 million displaced and about 30,000 have fled to Angola, according to the Catholic Church and the UN. The UN has identified at least 80 mass graves in the region.

These child soldiers that make up the local millitia in Congo have been reported to drink the blood of their victims in a magic ritual meant to make them invincible, the United Nations Commission on Human Rights (OHCHR) warned on Friday.

As gathered by the UN, most residents were convinced of the children’s magical powers, which created widespread fear “This generalised belief … may partly explain why a poorly armed militia, composed to a large extent of children, has been able to resist offensives by a national army for over a year,” the report, which is based on interviews with 96 people who had fled the violence to neighbouring Angola, says.

The Kamuina Nsapu militia, which regularly stages attacks in the central Kasai region, largely used boys and girls as fighters, many of them between the ages of 7 and 13, the report said. As part of the ritual, groups of girls shook their straw skirts and drank the victims’ blood.

The refugees also reported that local security forces and other officials actively participated in, fueled and occasionally led attacks.