Eight United Nations peacekeepers and at least 12 Congolese soldiers were killed in a joint military operation against rebels in the northeast of the Democratic Republic of Congo, which is facing a deadly Ebola outbreak, the Security Council said Thursday.

Ten peacekeepers were injured and one was missing after Wednesday’s operation that targeted Allied Democratic Forces rebels, said the United Nations spokesman, Stéphane Dujarric.

The Security Council’s statement said seven of the peacekeepers who were killed were from Malawi and one was from Tanzania.

The joint forces were attacked while conducting operations to dislodge the rebel fighters from a stronghold in Kididiwe, near the regional capital of Beni, a United Nations official said. The mission succeeded and a number of rebels were captured, the official added, speaking on condition of anonymity because he was not authorized to discuss the matter publicly.