More than 1,000 civilians were killed when Sudan’s Rapid Support Forces (RSF) seized the Zamzam displacement camp in Darfur in April, the United Nations reported on Thursday. The attack, which targeted one of the region’s most vulnerable populations, included the summary execution of roughly a third of the victims, according to the UN Human Rights Office.

The Zamzam camp, home to nearly half a million people displaced by Sudan’s long-running civil conflict, had been cut off from food and essential supplies for months before the assault from April 11 to 13. During the takeover, RSF forces reportedly carried out widespread killings, rapes, torture, and abductions. At least 319 people were executed either inside the camp or while attempting to flee.

“Such deliberate killing of civilians or persons hors de combat may constitute the war crime of murder,” said U.N. High Commissioner for Human Rights Volker Turk in a statement accompanying the 18-page report.

As reported in Reuters, the findings are based on interviews with 155 survivors and witnesses who fled to neighboring Chad. One harrowing account described RSF fighters shooting into a room where eight people were hiding, killing them on the spot.

The RSF did not immediately respond to requests for comment. The group has previously denied targeting civilians and said it would hold its forces accountable for any violations.

The April attack is considered a precursor to a later offensive on al-Fashir city in late October, where the RSF is accused of similar summary executions and kidnappings, leaving thousands unaccounted for.

The UN’s report underscores the ongoing humanitarian crisis in Darfur and raises urgent concerns about accountability for mass atrocities in Sudan.