KINSHASA, Congo (AP) — Rebels in eastern Congo killed at least 19 people and set fire to a health center and houses, authorities reported Sunday.

Gunmen suspected of being part of the Allied Democratic Forces, a militia with links to the Islamic State group, attacked civilians in Kirindera town, Carly Nzanzu, the former governor of North Kivu province, said in an interview with state media.

ADF attacks have killed dozens of people in several North Kivu villages in recent days. Congo’s authorities say people were slaughtered with guns, knives and machetes.

Aamaq, a news agency linked to the Islamic State group, posted a statement Saturday in which IS claimed responsibility for killing more than 35 “Christians” and wounding dozens in eastern Congo last week.

Conflict has simmered for decades in eastern Congo, where more than 120 armed groups fight for power, influence and resources, and some to protect their communities. The ADF has been largely active in North Kivu province but recently extended its operations into neighboring Ituri province.

Efforts to stem the violence against have yielded little. A nearly year-long joint operation by Uganda and Congo’s armies did not defeat or substantially weaken the Allied Democratic Forces, a panel of U.N. experts concluded in a December report.

The U.N. and human rights groups have accused the ADF rebels of maiming, raping and abducting civilians, including children. Earlier this month, the United States offered a reward of up to $5 million for information that could lead to the capture of the group’s leader, Seka Musa Baluku.