Atleast 60 people have been killed in an overnight attack by Islamic State-affiliated rebel group in eastern Congo, an official said.

The attack was reportedly carried by the Allied Democratic Force in Ntoyo, North Kivu, after residents gathered at a burial.

“The ADF attack caused around 60 deaths, but the final toll will be given later this evening because the territory has just deployed services to the area to count the number of beheaded people,” Col Alain Kiwewa, local administrator of the Lubero territory where Ntoyo is located, told The Associated Press.

“There were about 10 of them. I saw machetes. They told people to gather in one place and started cutting them. I listened to people screaming and I fainted,” a survivor who was present at the burial told the AP. She requested anonymity out of fear of reprisal.