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

The attack was carried out 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. The region is beset by a set of complex conflicts, including an increase in attacks by the ADF, which operates in the border region between Congo and Uganda. In July, the group carried out two large-scale attacks in Ituri province — a church attack killing at least 34 in Komanda and an earlier attack that killed 66 people in Irumu.

Despite joint operations by both Congo and Uganda to target the rebel group, the ADF, which pledged allegiance to the Islamic State in 2019, has continued to attack civilians.

The attacks worsen the plight of Congolese in the eastern region where several other conflicts are unfolding, including a major conflict between the Rwanda-backed M23 rebel groups and the central government.