Extremist rebels in eastern Democratic Republic of Congo have killed at least two dozen civilians in separate attacks this week, local authorities and a civil society group said Tuesday.

Allied Democratic Forces (ADF) rebels , who have links to the Islamic State group , killed 13 people in Mambasa territory, Ituri province , on Tuesday, said Christophe Munyanderu, Convention coordinator for the respect for human rights . Most of the victims were killed in their homes, he added.

In neighboring North Kivu province , the ADF killed at least 11 people with machetes and guns in Beni territory on Monday, said Colonel Charles Ehuta Omeonga, the region’s administrator.

Civilians have also been targeted in their homes, and the death toll is higher because some people are missing, he added.

Violence has been brewing for years in eastern DRC, where around 120 armed groups are fighting for power, land, minerals or the security of their communities.

In recent years, ADF attacks have intensified and spread to Goma, the main city in eastern Congo, as well as Ituri province.

Rights groups and the United Nations have accused the ADF of killing hundreds of people and kidnapping more, including large numbers of children.