Thousands of residents on Wednesday fled Sudan's capital, where witnesses said bodies lay in the street from fighting between the army and paramilitaries after a 24-hour truce failed to take hold.
Five days of fighting in Khartoum and elsewhere in the northeast African country have killed at least 185 people, according to the most recent UN toll.
Foreign diplomats have been attacked, and United Nations emergency relief coordinator Martin Griffiths said the UN had received "reports of attacks and sexual violence against aid workers."
Governments started planning to evacuate their citizens, among them many UN staff.
The violence erupted on Saturday between the forces of two generals who seized power in a 2021 coup: army chief Abdel Fattah al-Burhan and his deputy, Mohamed Hamdan Daglo, who commands the paramilitary Rapid Support Forces (RSF).
It followed a bitter dispute between them over the planned integration of the RSF into the regular army— a key condition for a final deal aimed at restoring Sudan's democratic transition.
"Life in Khartoum is impossible if this war does not stop," said Alawya al-Tayeb, 33, on her way out of the capital.
"I tried to make children not see the slain bodies on the streets," she said, adding that her children currently suffer from shock and will need treatment.
Deafening explosions rattled buildings and heavy gunfire was heard in Khartoum, as witnesses said plumes of thick black smoke emanated from buildings around the army headquarters in central Khartoum.
RSF fighters atop armored vehicles and pickup trucks laden with weapons swarmed the streets. Fighter jets roared overhead and fired on RSF targets, the witnesses said.
Civilians huddled in their homes were becoming increasingly desperate, with dwindling food supplies, power outages, and a lack of running water.
A 24-hour humanitarian ceasefire announced by South Sudan failed to take hold at its proposed start at 4 p.m. GMT on Tuesday.
On Wednesday, the RSF said it would "fully commit to a complete ceasefire," again from 4 p.m. GMT and for 24 hours. The army had made no comment on such a development.
Thousands of people took matters into their own hands and, according to witnesses, began leaving their homes in Khartoum, some in cars and others on foot, including women and children.
They said the streets were littered with dead bodies, the stench of which filled the air.
"We are now on our way to Madani to stay with our relatives after my family and kids lived through the terror of explosions," said Mohamed Saleh, 43, a government employee.
"We were very worried fighters would start storming homes."
The fighting has killed at least 185 people and injured more than 1,800, according to UN figures from Monday.
But the real toll is thought to be far higher with many wounded unable to reach hospitals, which are themselves being shelled, according to the official doctors' union.
Out of 59 main hospitals in Khartoum, about 39 are currently "out of service", said the union which reported "severe shortages" in remaining facilities.
Japan said its defense ministry had begun the "necessary preparations" to evacuate around 60 of its nationals from Sudan, including embassy staff.
Berlin aborted on Wednesday an evacuation attempt involving three military transport planes, which would have carried 150 citizens, according to German weekly Der Spiegel.
The US embassy in Khartoum said it started gathering citizens' personal details while urging them to remain indoors and stay away from windows.
"Due to the uncertain security situation in Khartoum and closure of the airport, there are no plans for [a] US government-coordinated evacuation," it tweeted.
The violence has also seen a US diplomatic convoy fired upon, the European Union's ambassador attacked at home and a Belgian humanitarian official with the EU hospitalized after being shot.
Aid groups have reported looting of medical and other supplies.
RSF has since Saturday captured a group of Egyptian soldiers in the northern city of Meroe. It said they have now been transported to Khartoum.
"They will be handed over [to Egypt] whenever there is a chance," it said in a statement.
The latest violence, at the end of the holy Muslim fasting month of Ramadan, came after more than 120 civilians had already been killed in a crackdown on regular pro-democracy demonstrations over the past 18 months.
Both generals have positioned themselves as saviors of Sudan and guardians of democracy -- in a country which has known only brief democratic interludes.
Saturday's outbreak of violence is the culmination of deep-seated divisions between the army and the RSF, which was created in 2013 by longtime autocrat Omar al-Bashir.
Burhan and Daglo toppled Bashir together in April 2019 following mass protests against his three decades of iron-fisted rule.
In October 2021, the pair led a military coup against the civilian government, which was installed following Bashir's ouster, derailing an internationally backed transition.
Burhan, a career soldier from northern Sudan who rose the through ranks under Bashir, has maintained his coup was "necessary" to include more factions into politics.
But Daglo, whose RSF emerged from the Janjaweed militia in Darfur, has since called the coup a "mistake" that failed to bring about change and invigorated Bashir's remnants.