The United Nations estimated on Wednesday that almost 3,000 people have been killed during the conflict in the Democratic Republic of the Congo (DRC).

According to the U.N. report, corpses are still decomposing in the streets of Goma, the regional capital city conquered by the M23 insurgents in late January.

Senior U.N. official Vivian van de Perre, deputy chief of the MONUSCO peacekeeping mission, said the situation in Goma remains “highly volatile, with persistent risks of escalation.”

“The mission’s key infrastructures in Goma are overwhelmed, with both U.N. personnel and Congolese seeking shelter within our premises,” she said.

Van de Perre was particularly concerned with the loss of the Kavumu airport in Bukavu, another provincial capital that came under assault by M23 forces on Wednesday. The rebels began their siege of Bukavu within 48 hours of declaring a “humanitarian ceasefire” that would ostensibly allow food and medical aid to reach civilians in Goma.

According to Van de Perre, losing the airports in both Goma and Bukavu “in the midst of an ongoing humanitarian and Internally Displaced Persons (IDP) crisis” would be “untenable” for the civilian population of the eastern Congo.

“We reiterate our call for the urgent reopening of Goma airport, as we need to evacuate wounded people and bring in humanitarian supplies and staff in,” said Stephane Dujarric, a spokesman for U.N. Secretary-General Antonio Guterres.

MONUSCO’s situation has rapidly deteriorated amid military and political chaos in the DRC, where armed forces from Uganda and Rwanda, plus a hundred militia groups, are involved in the conflict. Van de Perre asked for “clear guidance” from the U.N. Security Council (UNSC) because the situation is “changing literally every hour.”

MONUSCO said on Wednesday it has “ceased joint operations with Congolese armed forces” and “withdrawn from South Kivu, following Security Council mandates.”

South Kivu is the province that counts Bukavu as its capital city. MONUSCO has been actively supporting the Congolese military, known as the FARDC, until now.

The DRC government said on Thursday it will ask the U.N. Human Rights Council (UNHRC) to investigate “mass violations” of human rights in Goma. The DRC wants the U.N. to send a “fact-finding mission” to the city as soon as possible.

Van de Perre said she was aware of one atrocity in particular: a mass jailbreak at Goma’s Munzenze Prison that appears to have been initiated after M23 rebels breached the city’s defenses.

Although confirmed details are scarce, including firm evidence of whether M23 deliberately caused the jailbreak, early reports said hundreds of female inmates were raped and burned alive during the chaos. M23 has refused to allow investigators to visit the site to gather more evidence.

“There was a major prison breakout of 4,000 escaped prisoners. A few hundred women were also in that prison. They were all raped and then they set fire to the women’s wing. They all died afterwards,” Van de Perre said.

M23 held a stadium rally in Goma on Thursday to inform residents they were now permanently in control of the city, which they described as “liberated and sanitized” by their presence. The insurgents took control of Goma with the assistance of 4,000 troops from neighboring Rwanda, which has long supported M23.

“I ask you to sleep well because we bring you security; this is our priority. Starting next week, the children return to school. Let all state agents return to their offices. The displaced people are returning to their homes,” M23 political leader Corneille Nangaa told the crowd at the stadium.

Also on Thursday, the Africa Centers for Disease Control and Prevention (Africa CDC) confirmed that services have been disrupted at the National Institute of Biomedical Research, a laboratory in Goma that studies Ebola and mpox (monkeypox), among other dangerous diseases.