The United Nations Secretary-General has condemned the killing of UNICEF staff member Karine Buisset in a drone strike in Goma, in the conflict-ravaged east of the Democratic Republic of the Congo, calling the attack an unacceptable assault on humanitarian workers.

Buisset, a French national, was killed when a drone hit a private residence near Lake Kivu that was being used to house aid workers, according to local residents and the M23 rebel group. The building lies only a short distance from the home of former Congolese president Joseph Kabila Kabange, underscoring the volatility of the area.

UN spokesperson Stéphane Dujarric told reporters in New York that Buisset was a committed humanitarian who had devoted her career to supporting children and families caught up in conflict and crisis. He said the UN and UNICEF extended their deepest condolences to her family, friends and colleagues, and stressed that her death was a stark reminder of the dangers faced daily by aid workers in the region.

M23 rebels blamed the Congolese government for the drone strikes, which they said killed three people. That toll could not be independently verified, and authorities in Kinshasa did not immediately respond to requests for comment. The strikes reportedly hit both the lakeside area and the residence where Buisset was staying.

Dujarric reiterated the UN’s demand that all parties to the conflict respect international humanitarian law. “The parties must ensure the protection of civilians and those providing lifesaving assistance. Humanitarian personnel must never be a target,” he said.

According to the UN Office for the Coordination of Humanitarian Affairs, Buisset is the second aid worker killed in the DRC this year. Since January, at least dozens of security incidents affecting humanitarian staff have been reported nationwide, including attacks, looting and intimidation. Last year, more than 650 such incidents were recorded, with 13 aid workers killed and 41 injured across the eastern provinces of North Kivu, South Kivu, Ituri, Tanganyika and Maniema.

Peacekeepers from the UN mission in the country, MONUSCO, were dispatched to the scene of the strike to provide emergency support and conduct an initial assessment. The killing is expected to intensify scrutiny of the warring parties in eastern Congo and renew calls for stronger protections for civilians and the humanitarian workers trying to assist them.