A weeks-long power struggle exploded into deadly violence Saturday between the forces of two generals who seized power in a 2021 coup, Sudan's army chief Abdel Fattah al-Burhan and his deputy, Mohamed Hamdan Daglo, who commands the powerful paramilitary Rapid Support Forces (RSF).
Analysts say the fighting in the capital of the chronically unstable country is unprecedented and could be prolonged, despite regional and global calls for a ceasefire as diplomats mobilise.
Battles have also taken place throughout the vast country, and there are fears of regional spillover.
Terrified residents of the capital are spending the last and holiest days of Ramadan watching from their windows as tanks roll through the streets, buildings shake, and smoke from fires triggered by the fighting hangs in the air.
The conflict has seen air strikes, artillery and heavy gunfire.
Those compelled to venture out face queues for bread and petrol at outlets which are not shuttered. Residents are also dealing with power outages.
Volker Perthes, the head of the United Nations mission to Sudan, told the Security Council in a closed-door session, that at least 185 people have been killed and another 1,800 wounded.
"It's a very fluid situation so it's very difficult to say where the balance is shifting to," Perthes told reporters after the meeting.
Earlier Monday, UN Secretary-General Antonio Guterres again called on Sudan's warring parties to "immediately cease hostilities". He warned that further escalation "could be devastating for the country and the region."
Vital aid suspended
Medics in Sudan had earlier given a death toll of nearly 100 civilians and "dozens" of fighters from both sides, but the number of casualties was thought to be far higher, with many wounded unable to reach hospitals.
The official doctors' union warned fighting had "heavily damaged" multiple hospitals in Khartoum and other cities, with some completely "out of service".
The World Health Organization had already warned that several of Khartoum's nine hospitals receiving injured civilians "have run out of blood, transfusion equipment, intravenous fluids and other vital supplies".
In the western region of Darfur, international medical aid organisation Doctors Without Borders (MSF) reported receiving 136 wounded patients at the only hospital in El Fasher still operating in North Darfur state.
"The majority of the wounded are civilians who were caught in the crossfire -- among them are many children," MSF's Cyrus Paye said.
Due to limited surgical capacity, "11 people died from their injuries in the first 48 hours of the conflict."
Three UN World Food Programme staff were also among those killed, on Saturday in Darfur, where humanitarian missions have had medical and other supplies looted, according to Save the Children and MSF.
A number of organisations have temporarily suspended operations, in a country where one-third of the population needs aid.
Diplomatic manoeuvres seemed to ramp up Monday, as the fighting showed no signs of abating.
Influential northern neighbour Egypt announced it had discussed with Saudi Arabia, South Sudan and Djibouti -- all close allies of Sudan -- "the need to make every effort to preserve stability and safety".
The Gulf emirate Qatar spoke to African Union commission head Moussa Faki Mahamat, who is planning to "immediately" undertake a ceasefire mission.
There are, however, no more civilian flights arriving in Khartoum, where fighting has damaged aircraft.
On Twitter Daglo called on the international community to intervene against Burhan, branding him a "radical Islamist who is bombing civilians from the air".
"We will continue to pursue Al-Burhan and bring him to justice," said Daglo, whose RSF and its predecessor the Janjaweed in Darfur have previously been accused of atrocities and war crimes.
Army statements call the RSF "a rebel militia" intent on "engaging near populated areas".
The fighting broke out after bitter disagreements between Burhan and Daglo over the planned integration of the RSF into the regular army -- a key condition for a final deal aimed at ending a crisis since the 2021 coup, which derailed a transition to democracy.
Both claim to be in control of key sites, including the airport and the presidential palace -- none of which could be independently verified.
On Monday, the army resumed broadcasting on state TV.
The few grocery stores remaining open warned they will only last a few days if no supplies can enter the city.
Witnesses noted militiamen had begun driving past in private passenger vehicles with no licence plates.
While Sudan has endured decades of multiple bitter civil wars, coups and rebellions since independence, Sudanese analyst Kho lood Khair said the level of fighting inside the capital was "unprecedented".
The generals' coup derailed a transition to civilian rule following the 2019 ouster of strongman Omar all-Bashir, triggering international aid cuts and sparking near-weekly protests met by a deadly crackdown.