Allied Democratic Forces rebels with ties to the Islamic State group have long operated in the border area. The United Nations said last week that almost 200 people have been killed there this year.

Capt. Anthony Mulushayi, spokesperson for the Congolese army in North Kivu province, on Tuesday said the attackers earlier that day set a local hospital on fire and took a number of civilians into the bush. He said the army responded, killing four of the attackers and rescuing four people.

A local civilian leader, Kakule Mwendapeke, said the civilian toll was higher, with at least 17 killed, and others are missing after being kidnapped. Survivors fled their villages to seek refuge in nearby urban centers including Beni and Mangina.

Eastern Congo has been ravaged by conflict for decades as more than 120 armed groups fight for control of valuable mineral resources and some try to protect their communities. Mass killings by rebels are frequent. The violence has driven over seven million people to flee their homes, the U.N. has said.

Bintou Keita, the top UN envoy to Congo, warned last week that violence is escalating, with thousands of human rights abuses, including rapes and gender based violence, reported this year.