At Least 36 people were killed by extremists in conflict-riddled eastern Congo, the military said on Thursday. The Allied Democratic Forces, a rebel militia with links to the Islamic State group, killed civilians in Mukondi village in North Kivu province, said Congo army spokesman in Beni town, Capt. Anthony Mwalushayi.

“The enemy made the incursion into the chiefdom of Bashu and managed to kill 36 of our compatriots and burned some residents’ huts in the area,” he said. Several people were injured in Wednesday night’s attack and an investigation has been launched to search for the missing, he said.Conflict has been simmering in eastern Congo for decades as 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 has recently extended its operations into neighboring Ituri province and to areas near the regional capital, Goma.

The ADF rebels are accused by the U.N. and rights groups of targeting, 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.

The attack began around 7 p.m. Wednesday when men with guns and machetes stormed the village and started indiscriminately killing people, witnesses told The Associated Press by phone.

“The rebels came and they first burned houses. Then everyone who came out of his house was either cut up with machetes or shot dead,” said Saddam Patangoli, a resident of Mukondi village who fled the attack and returned to his home the following day. They also abducted many civilians, he said.

Some people are blaming the incident on the Congo army’s lack of presence in the area. “The area is not covered by soldiers of the Congolese armed forces,” said Kasereka Alexis, a survivor of the attack. “That’s why the enemy took advantage of coming to massacre us,” he said.

ADF’s persistence and evolution in eastern Congo for nearly three decades exposes the extent of the challenge facing the government, say analysts. “The group is infamous for its extreme violence and its link to Islamic State provides access to regional jihadist networks and funding sources,” said Benjamin Hunter, Africa analyst for Verisk Maplecroft a risk assessment company.