Thousands of residents have fled Khartoum as fighting continued across the city for a fifth day and many countries began preparations to evacuate their citizens from Sudan. Attempts to resurrect a US-brokered ceasefire between the army and paramilitary forces that failed to hold on Tuesday did not reassure many inhabitants of the capital, which suffered some of the most intense clashes yet seen as rival factions battled for control of the airport, defence headquarters and other key strategic sites. Germany and Japan are reportedly planning the evacuation of their citizens but the US embassy in Khartoum said that “due to the uncertain security situation in Khartoum and closure of the airport, there are no plans for [a] US government-coordinated evacuation” for the moment. Internal United Nations documents seen by the Guardian describe a “nightmare scenario” that appears to have caught the organisation unprepared. A security report describes looting and a series of attacks on UN staff, mainly by Rapid Support Forces (RSF) personnel, in Khartoum and elsewhere but says immediate evacuation is impossible as long as Sudanese airports remain out of action. The possibility of an evacuation by road – an operation fraught with danger – is being considered. Senior UN management have told staff in the most dangerous locations that they must make their own decisions about how to remain safe, provoking anger. Some UN and other aid workers have been targeted with sexual violence, officials said. The fighting has pitted army units loyal to Gen Abdel Fattah al-Burhan, the head of Sudan’s transitional governing sovereign council, and the RSF, led by Gen Mohamed Hamdan Dagalo, known as Hemedti, who is deputy head of the council. Their power struggle has derailed a shift to civilian rule and raised fears of a long, brutal civil war. The director-general of the UN’s World Health Organization, Tedros Ghebreyesus, said on Wednesday that at least 270 people had been killed and more than 2,600 wounded since fighting began, without giving a breakdown of civilians and combatants killed. According to the Sudan doctors’ union, the deaths of 30 civilians had been confirmed on Tuesday, though the total is likely to be much higher. There were also 245 civilians reported injured. Two-thirds of civilian fatalities were recorded outside Khartoum, the new statistics showed, indicating how much of the fighting was occurring in remote regions. In Nyala, in the restive South Darfur state, six people died and 63 were wounded as a main food market was set on fire and the offices of aid agencies looted. Tensions remained high in the city on Wednesday night, local activists said. In al-Fashir, in North Darfur, nine people died and 36 were injured, while in Zalingei, in Central Darfur, five people died and 60 were wounded. There were also reports of airstrikes and fighting around the international airport at the town of Merowe, a well-known archaeological site and commercial centre 270 miles (440km) north of Khartoum. “The situation for civilians is not good anywhere in the country, but it is especially bad in the capital, Nyala and Merowe,” said one doctor contacted by the Guardian in Khartoum. “Four of my colleagues have been killed. Almost all the main hospitals are suffering acute shortages in medical staff, medicine, water, electricity, fuel and food. “Many patients have been sent home. For civilians, the main problems is the cut-off water and electricity supplies. I am personally in a place where there is no supply of water and electricity for two days.” The doctor asked for anonymity for fear of reprisals. Across Sudan, prices of staples such as sugar, milk, flour and oil are increasing, aggravating an acute economic crisis. Aid workers in al-Qadarif said long-life items such as dehydrated milk had disappeared from shelves. UN agencies said many of their programmes across the vast country, already in a precarious humanitarian situation, had been suspended. On Wednesday morning, thousands of Khartoum residents began leaving their homes, some in cars and others on foot. “Khartoum has become a ghost city,” said Atiya Abdalla Atiya, secretary of the Sudanese Doctors’ Syndicate, who was still in the capital. The exodus continued throughout the day, despite a statement by the RSF that it would “fully commit to a complete ceasefire”, again from early evening and for 24 hours. Alawya al-Tayeb, 33, on her way out of the capital, said she had tried to shield her children from the sight of dead bodies on the streets as the family had left the capital. “Life in Khartoum is impossible if this war does not stop,” she said. Saturday’s outbreak of violence is the culmination of deep-seated divisions between the army and the RSF, which was created in 2013 by the autocrat Omar al-Bashir. The conflict between the military and the RSF risks drawing in other powers keen to win influence and access to precious resources in Sudan, analysts fear.