While fighting rages, relief efforts have stalled after more than two months of fighting between rival generals. Houses in Khartoum shook from the fighting that continued unabated, residents said, with entire families sheltering in place, running low on vital supplies in the baking summer heat.
Entire districts of Khartoum no longer have running water, and those who remain in the city have had no electricity at all since Thursday, several residents told AFP.
The battle for power between army chief Abdel Fattah al-Burhan and his former deputy, RSF commander Mohamed Hamdan Dagalo, has killed more than 2,000 people, according to the Armed Conflict Location and Event Data Project.
The deadliest violence has raged in Darfur, a vast western region on the border with Chad where the UN has warned of possible crimes against humanity and said the conflict has taken an "ethnic dimension".
In the South Darfur state capital Nyala, residents said they had been caught in the crossfire. They reported battles, shelling and artillery strikes.
"Civilians were killed, and wounded are arriving at the hospital," a medic told AFP on condition of anonymity.
The UN on Saturday urged "immediate action" to stop killings of people fleeing El Geneina, the West Darfur state capital, by Arab militias aided by the paramilitaries.
The Geneva-based UN rights office said witnesses had given "corroborating accounts" of militias targeting men from the non-Arab Masalit people.
It said all but two of the 16 people it interviewed testified they had witnessed "summary executions" and the targeting of civilians on the road from El Geneina to the border between June 15 and 16.
"All those interviewed also spoke of seeing dead bodies scattered along the road – and the stench of decomposition," the UN said.
Two-thirds of health facilities in the main battlegrounds remain out of service, according to the Sudanese doctors' union. The few hospitals still operating are extremely low on medical supplies and struggling to obtain fuel to power generators.
The UN says a record 25 million people - more than half of Sudan's population - are in need of aid and protection.
Aid has reached at least 2.8 million people, the UN said, but agencies report major hurdles to their work, from visas for foreign humanitarians to securing safe corridors.
"The army is [...] loath to let aid into the capital, fearing that packages will end up in the RSF's hands" as has happened before, "allowing the paramilitary to hold out longer", according to think-tank the International Crisis Group (ICG).
The United States, which along with Saudi Arabia sought to mediate between the warring sides and ensure humanitarian aid can reach those in need, said Thursday it had put its efforts on hold.
"Both sides seek to use the humanitarian talks for tactical advantage [...] with the military demanding that the RSF vacate residential areas and the RSF demanding that the army cease its aerial barrages," ICG said this week in a report.
No side appears willing to stand down, exacerbating the risk of prolonged conflict with regional ramifications.
More than 150,000 people have fled Darfur over the border to Chad, according to the International Organization for Migration. Chad, which already hosted more than 680,000 refugees, needs massive financial and technical support to confront this "unprecedented migratory crisis," Prime Minister Saleh Kebzabo said on Saturday.
Dagalo's RSF have their origins in the Janjaweed militias which former strongman Omar al-Bashir unleashed in response to a rebellion by ethnic minorities in Darfur in 2003, drawing charges of genocide, war crimes and crimes against humanity.
"A collapsed Sudan could create a haven for transnational militants [...], mercenaries and traffickers who could plague the country's neighborhood for years to come," ICG warned.
Maha Abdullah, 50, a tearful Sudanese housewife who was able to reach Saudi Arabia for the hajj pilgrimage, sees only one solution: "It needs God's intervention to change things."