Two staff members of the foreign aid group Tearfund were killed on Sunday when their convoy was attacked in Butembo city, North Kivu province, eastern Congo, the organization announced. This incident is part of an ongoing series of attacks targeting aid groups and residents in the region.

The aid workers were killed after arriving in Butembo, an area plagued by conflicts between armed rebels and Congolese security forces. The identity of the attackers remains unknown, but the region is known to host over 120 armed groups involved in violent incidents often linked to control over gold and other resources.

The United Nations Office for the Coordination of Humanitarian Affairs in Congo reported over 170 security incidents targeting humanitarian workers this year, resulting in at least four deaths and more than a dozen abductions. The UN has called for increased protection for aid workers.

“At a time of immense humanitarian need, it is unacceptable that those working to help affected people are being attacked and killed,” stated Bruno Lemarquis, the humanitarian coordinator for Congo.

Violence in North Kivu has intensified recently as security forces clash with rebels. Last week, mortar shelling targeted a South African military base, part of a regional peacekeeping mission, killing two people. Rebels have also captured more villages in the area.

The M23 rebel group, reportedly linked to neighboring Rwanda, has been particularly active, seizing strategic towns and controlling about half of North Kivu province, according to Richard Moncrieff, the Crisis Group’s Great Lakes region director.