Democratic Republic of Congo authorities accused an extremist group with ties to Islamic State of killing at least 26 people on Monday night in the Central African nation (Oct. 23), Voice of America reports.

Nicolas Kikuku, the mayor of Oicha, said the assault occurred around 11 p.m. in his North Kivu province town, located in eastern DRC. Four wounded victims went to the hospital after the attack, which Kikuku attributed to the Allied Democratic Forces (ADF).

ADF originated in Uganda and now operates in eastern Congo. Uganda and the DRC joined forces two years ago to eradicate ADF. In September, Uganda said it killed more than 560 militants and destroyed several of their camps.

Antony Mwalushayi, a spokesperson for Congo’s army, said the Islamist fighters used machetes instead of guns to avoid alerting nearby troops, Reuters reports, adding that the assault on civilians was retaliation for recent military strikes against them.

"The enemy was divided into three groups. The first group was there to prevent the intervention of the military, the second group was there to loot the stores of the civilian population and the third group was there to silently slaughter our population with machetes," Mwalushayi said.

ADF has grown more deadly after receiving money from the Islamic State, according to The Washington Post, citing information from defectors and research published in June on the group’s finances by George Washington University and Texas-based Bridgeway Foundation.

“The money means innocent people are dying horrific deaths,” Tara Candland, one of the report’s authors, told The Post.

ADF has blown up churchgoers, conducted suicide bombings, organized jailbreaks, and beheaded and burned people alive over the past year.

Founded in 1995, ADF fled from Uganda’s military to Congo in the early 2000s. Uganda sent troops across its border to continue its campaign to eliminate the Islamist fighters.