UN High Commissioner for Human Rights Michelle Bachelet demands "impartial and independent" investigations into the attacks in the volatile African region.
Ongoing armed clashes in Sudan's troubled Darfur region have killed at least 213 people in recent days, with the UN human rights chief saying she was "appalled" at the spike in violence.
Members of the Massalit community and Arab fighters have clashed since Friday in and around the West Darfur state capital El Geneina, the latest ethnic violence in the vast, arid and impoverished region long awash with guns.
Heavy shooting was reported on Wednesday evening in El Geneina, said Adam Regal from the General Coordination for Refugees and Displaced in Darfur, an independent aid group.
"Guns are being fired extensively," Regal said. "The situation is very dangerous."
Fighting amidst coup
The fighting, which comes as Sudan grapples with the fallout from a coup six months ago led by army chief Abdel Fattah al Burhan, has seen hospitals attacked, a police station destroyed and a market burned to the ground, according to the United Nations.
At least 213 people have been killed in three days of violence, according to the state governor.
The clashes have centered on Krink, a locality of nearly 500,000 people some 1,100 kilometres west of Sudan's capital Khartoum.
West Darfur governor Khamees Abkar called the attacks a "massive crime", noting that 201 people were killed and 103 wounded on Sunday alone.
It is the latest in several rounds of recent clashes pitting the Massalit – largely settled farmers – against semi-nomadic Arab pastoralist groups.
"I am appalled," the UN High Commissioner for Human Rights Michelle Bachelet said in a statement on Wednesday, demanding "impartial and independent" investigations into the attacks.
"I am concerned that this region continues to see repeated, serious incidents of intercommunal violence, with mass casualties," she said.
The UN Security Council in New York held an urgent closed-door meeting about the crisis on Wednesday.
Heavy fighting initially erupted on Friday when at least eight people were killed in the Krink region, with gunmen reportedly attacking Massalit villages in retaliation for the killing of two comrades.
The UN said more than 1,000 armed members of the Arab Rizeigat community then swept into the town.
Many militants in the region are heavily armed, often driving pickup trucks mounted with machine guns.
Krink town "was completely destroyed including government institutions," state Governor Abkar said. "It is a crime against humanity."
The governor lashed out at government forces tasked with securing Krink and its environs for "withdrawing without any justification" as the main attacks began early Sunday.
The UN humanitarian agency OCHA, quoting local sources, said that the police station in Krink was set on fire, the hospital attacked, and the market was "looted and burned".
Food aid handouts for more than 60,000 people by the UN's World Food Programme have been suspended.
"Nearby villages have also been attacked," the UN added.
Fighting on Monday spread to the state capital El Geneina, where more deaths were reported.
READ MORE: Hundreds killed in Sudan’s Darfur clashes