Story highlights "It's dozens and dozens, scores of casualties," the head of the U.N. Security Council says 
 
 About 15,000 to 20,000 civilians have fled to United Nations bases in the city, he says 
 
 State Department says U.S. Embassy suspending normal operations until further notice 
 
 Sporadic gunfire still rattling Juba, diplomats say 
 
 The death toll from violence in South Sudan is "heavy," the United Nations said Tuesday, and thousands of people have sought refuge in the organization's compounds in Juba. 
 
 Gunfire rang out again in the capital of in Africa's newest nation just hours after the country's President said his forces had halted a coup attempt. 
 
 Clashes, which began on Sunday evening, have left hundreds in urgent need of medical care, the International Committee of the Red Cross (ICRC) said. 
 
 Gerard Araud, the French representative to the United Nations and the current President of the Security Council, said precise figures on the death toll weren't available. 
 
 "But it's heavy," he said. "It's dozens and dozens, scores of casualties, it's really not a minor incident." 
 
 Officials at the United Nations are "extremely concerned" about the violence, Araud said, due to the high number of casualties and because the fighting appears to be between different ethnic groups in South Sudan. 
 
 On Tuesday, sporadic gunshots were heard in the area of Tonping, the U.S. Embassy said on its Twitter feed, quoting U.N. radio. It recommended that U.S. citizens currently in the country depart immediately. 
 
 Women and children carrying bags, kettles, pots and basic belongings arriving at a U.N compound to seek shelter could be seen in pictures posted on the U.N. mission in South Sudan (UNMISS) Facebook page. 
 
 Araud said Tuesday evening that around 15,000 to 20,000 civilians were taking refuge in the two UNMISS compounds in Juba, putting a strain on supplies of medicine, food, water and security resources. 
 
 In a televised address Monday, South Sudan President Salva Kiir blamed soldiers loyal to his sacked deputy Riek Machar for starting the fighting Sunday evening. 
 
 Dressed in fatigues, he said the government was in full control of the capital and announced a nighttime curfew. 
 
 Ten people were arrested in connection with the foiled coup, according to a statement posted Tuesday on the South Sudan government website. 
 
 Hundreds in need of medical care 
 
 The ICRC said it was providing Juba's two major hospitals with support, such as wound-dressing materials, to cope with the heavy influx of patients. 
 
 More than 300 people have been admitted to Juba Teaching Hospital and Juba Military Hospital over the past two days, it said. 
 
 "We know there are more people who need care, but they are having difficulty reaching healthcare facilities because of the security situation and the lack of available transportation," Felicity Gapes, an ICRC delegate leading the medical response on the ground, said in a statement. 
 
 "Staff in both hospitals have been working around the clock, but they are struggling because of the sheer volume of patients and the severity of the injuries." 
 
 The United Nations said Secretary-General Ban Ki-moon spoke with Kiir by phone Tuesday, expressing his concern about the fighting. 
 
 He urged "all parties to cease hostilities immediately, and called on the government to exercise restraint in the management of the situation and to guarantee the protection of all civilians regardless of their ethnicities." 
 
 Deep-running tensions 
 
 Kiir's dismissal of his Cabinet in July further inflamed deep tensions between his Dinka community and Machar's Nuer community. 
 
 South Sudan formally split from Sudan in 2011 following a referendum, after decades of conflict. Numerous armed groups remain active in the oil-rich country. 
 
 UNMISS said Hilde F. Johnson, special representative of the U.N. secretary-general, called on "all parties in the current situation to refrain from any community-motivated violence." 
 
 "At a time when unity among South Sudanese is more needed than ever, I call on the leaders of this new country and all political factions and parties, as well as community leaders to refrain from any action that fuels ethnic tensions and exacerbates violence," Johnson said. 
 
 Juba's international airport remained closed. And with phone networks sketchy, embassies were turning to social media to stay in touch with their citizens, mainly calling on them to stay home and avoid unnecessary movement. 
 
 The State Department said U.S. citizens currently in South Sudan should leave immediately, and it ordered the departure of non-emergency U.S. government personnel from the country. 
 
 "The Embassy is also suspending normal operations until further notice and cannot provide routine consular services to U.S. citizens in South Sudan," it said. 
 
 The African Union said it was "deeply concerned" about the events in South Sudan, urging the government, leadership and other stakeholders to exercise maximum restraint and avert any further escalation. ||||| Fresh clashes have broken out in the South Sudanese capital Juba, and at least 66 soldiers have been killed, a day after President Salva Kiir said security forces had put down an attempted coup by supporters of his former deputy. 
 
 The US embassy said on its Twitter account late on Tuesday that that all of its citizens in the country should "depart immediately". The account tweeted that it would outline evacuation options on Wednesday morning. 
 
 "So far we have lost seven soldiers who died while they were waiting for medical attention and a further 59 who were killed outside," doctor Ajak Bullen said on the local Radio Miraya. 
 
 Poor communications in Juba, where the mobile phone system has not operated since Monday evening, meant it was difficult to obtain a broad picture of the number of dead during the clashes, which have involved heavy arms and artillery. 
 
 
 
 Kiir said on Monday the fighting between army factions was a bid to seize power by the former vice president, Riek Machar, whom he sacked in July. 
 
 The two men, from different ethnic groups, which have clashed in the past, have long been political rivals. Analysts said divisions between them run deep and rivalries in army ranks have long simmmered. 
 
 Al Jazeera's Rawya Rageh, reporting from neighbouring Nairobi, spoke to South Sudan's Information Minister Michael Makuei Lueth who confirmed at least 10 very senior former government officials have been arrested, including six cabinet ministers. The government named the men on its website. 
 
 There are conflicting reports about the whereabouts of Riek Machar. The government claims he is on his way to Unity State, whereas Machar's spokesperson said he is in fine condition and "very much still in Juba", Rageh said. 
 
 Heavy weapons 
 
 Gunfire - including the sporadic firing of heavy weapons - resumed in the early hours of Tuesday and was still audible at 9am (0600 GMT). It appeared to come from a military headquarters, a few kilometres from the centre of town. 
 
 Residents near Juba airport, which has been closed since Monday, were woken before dawn by gunshots and blasts, a UN worker said. Others also reported bouts of shooting. 
 
 The streets of Juba were deserted, with only military vehicles to be seen and civilians barricaded in their homes. 
 
 Kiir had said in a statement on Monday that security forces had regained control, although a dawn-to-dusk curfew had been imposed. 
 
 "The attackers went and [the] armed forces are pursuing them," Kiir said. "I promise you today that justice will prevail." 
 
 Details of the claimed coup remained sketchy, but South Sudan's Foreign Minister Barnaba Marial Benjamin told the Associated Press news agency that troops in the main army base raided a weapons store in Juba but were repulsed. 
 
 Civilians take refuge 
 
 The UN deputy special representative for South Sudan, Toby Lanzer, told Al Jazeera on Tuesday that about 16,000 civilians were now taking refuge from the fighting in two UN compounds. 
 
 "We will of course do everything we can do protect people. Many people who are coming require health care of all types," he said. 
 
 "Some people have been injured. We've got challenges of a variety - and the water and sanitation situation is also something that we are grappling with." 
 
 Tension had been mounting in South Sudan since Kiir's sacking of Machar. The men belong to different ethnic groups - Kiir to the Dinka, the most powerful, and Machar to the Nuer, but it is not clear whether this latest tension is due to ethnic or political divisions. 
 
 Machar, who has expressed a willingness to contest the presidency in 2015, told Al Jazeera in July that if the country is to be united it cannot tolerate "one man's rule or it cannot tolerate dictatorship." 
 
 His sacking, part of a wider dismissal of the entire cabinet by Kiir, had followed reports of a power struggle within the ruling party. 
 
 South Sudan's government has struggled to create a functioning state since it declared independence from Sudan in 2011 after years conflict with Khartoum during a war that often saw south-south clashes. ||||| Internally displaced boys stand next to barbed wire inside a United Nations Missions in Sudan (UNMIS) compound in Juba December 19, 2013. 
 
 An internally displaced man holds his son inside a United Nations Missions in Sudan (UNMIS) compound in Juba December 19, 2013. 
 
 A contingent of peacekeepers from the United Nations Mission in the Republic of South Sudan (UNMISS) guide civilians arriving at the UN compound in the outskirts of South Sudan's capital Juba, in this December 16, 2013 handout provided by UNMISS. 
 
 Soldiers from the peacekeeping force of the United Nations Mission in the Republic of South Sudan (UNMISS) participate in a routine patrol at their compound in the outskirts of South Sudan's capital Juba, in this December 16, 2013 handout provided by UNMISS. 
 
 Medic peacekeepers from the United Nations Mission in the Republic of South Sudan (UNMISS) treat civilians at their compound in the outskirts of South Sudan's capital Juba, in this December 19, 2013 handout provided by UNMISS. 
 
 JUBA African mediators said they held "productive" talks on Friday with South Sudan's President Salva Kiir, trying to prevent an almost week-long conflict plunging the world's newest nation into an ethnic civil war. 
 
 In a sign of the nervousness among South Sudan's neighbors, Ugandan soldiers flew in to help evacuate their citizens. Two anonymous military sources said they would also help secure the capital, which lies about 75 km (50 miles) from Uganda's border. 
 
 Kiir, a member of the Dinka ethnic group, has accused his former vice president Riek Machar, a Nuer who was sacked in July, of attempting to seize power by force. 
 
 Fighting that began on Sunday in the capital Juba has swiftly spread, and U.N. staff have reported hundreds killed. 
 
 Kiir has said he is ready for dialogue. Machar told French radio he was ready to "negotiate his departure from power" and said the army could force Kiir out unless he quit. 
 
 As fighting has moved out of the capital, it is increasingly driven by ethnic loyalties as much as political rivalries. 
 
 The U.N. said on Friday at least 11 people from the ethnic Dinka group had been killed during an attack by thousands of armed youths from another ethnic group on a U.N. peacekeeping base in Jonglei state. Two Indian peacekeepers died. 
 
 The United Nations had earlier said at least 20 people were killed, and South Sudan's government said earlier 54 Dinka had been killed in the incident. The United Nations mission in South Sudan is still trying to verify the exact number of dead. 
 
 Deputy U.N. peacekeeping chief Edmond Mulet told the U.N. Security Council on Friday 35,000 civilians were sheltering at U.N. bases across the country. 
 
 OIL 
 
 Fighting has spread to oilfields vital to the impoverished new state's economy and dependent on foreign workers. Soldiers from the rival factions clashed at a barracks near the town of Bentiu, capital of the oil-producing Unity State. 
 
 Some 200 oil workers sought refuge in a U.N. base on Thursday. China National Petroleum Corp, one of the main operators, said it was flying 32 workers out of one field to Juba, according the Chinese state news agency Xinhua. 
 
 "It's difficult to find plane providers to fly to some of these remote air strips. The situation on the ground is very fluid and we can't be absolutely confident about exact rebel locations and which airfields they may be controlling," said one security analyst, who did not wish to be identified. 
 
 The mediation team visiting Juba included ministers from Kenya, Uganda, Djibouti and Somali, and African Union and United Nations representatives. It was the first peace initiative since clashes erupted. 
 
 "We had a very productive meeting with his excellency President Salva Kiir and we will continue consultations," Ethiopian Foreign Minister Tedros Adhanom, who is leading the African delegation, told reporters before returning to talks. 
 
 The fighting worries neighboring states, which fear new instability in a volatile region. It threatens the halting steps towards the creation of a functioning state in a country which declared independence from Sudan in 2011 after decades of war. 
 
 "Some troops from (Uganda's) Special Forces Command - I can estimate in hundreds - left for Juba yesterday," said a source in the Command, a unit led by President Yoweri Museveni's son. 
 
 "They will mainly be involved in securing the capital," he said. Some had gone by plane and others would travel by road. 
 
 "They're not going to participate in the skirmishes between Kiir and Machar." 
 
 President Barack Obama said the United States had sent 45 military personnel to protect the embassy and U.S. employees. 
 
 "This force will remain in South Sudan until the security situation becomes such that it is no longer needed," he said in a letter to Congress. 
 
 TRADE HALTED 
 
 A Kenyan transporters' body said trade through landlocked South Sudan had ground to a halt, with hundreds of trucks stuck at border crossings with Uganda and Kenya. 
 
 "We have a military coup in our hands which is causing a lot of instability in the country and is being played up in certain areas as if it is a racial ethnic war, which is not the case," Foreign Minister Barnaba Marial Benjamin told Reuters. 
 
 "We don't want to encourage what happened in Rwanda," he said, referring to the 1994 genocide there. 
 
 Clashes in Bor town, where Nuer in 1991 massacred Dinka, have fuelled the fears of an all-out ethnic war. Nuer commander and Machar ally, Peter Gadet, now controls Bor, officials said. 
 
 Political tensions between the two politicians had been mounting since Kiir, facing growing public frustration about the slow pace of development, sacked Machar. 
 
 The former vice president said he wanted to run for office and accused Kiir of acting like a dictator. 
 
 Speaking to France's RFI radio, Machar said that unless Kiir quit office "I think the people will depose him, in particular, influential people in the army." 
 
 Before the fighting erupted, Kiir accused his rivals of reviving the kind of splits in the ranks of the ruling SPLM party that led to bloodshed in 1991. But analysts said he had raised the stakes by branding initial clashes a coup attempt. 
 
 (Additional reporting by Drazen Jorgic in Nairobi, Aizu Chen in Singapore, Maggie Fick in Cairo, Elias Biryabarema in Kampala, Lou Charbonneau in New York and Joseph Akwiri in Mombasa; Writing by Edmund Blair; Editing by Andrew Roche and Jonathan Oatis)
– The State Department today issued a travel warning for South Sudan, recommending that all Americans "depart immediately," as violence rises in the wake of an attempted coup. That includes non-emergency US personnel, who have already been ordered to depart, forcing the US to suspend normal operations at its embassy there until further notice. At least 66 soldiers have been killed so far in clashes in Juba, the capital of the world's newest country, al-Jazeera reports. Gunshots rang out within earshot of the embassy, and military vehicles roamed the mostly empty streets as residents barricaded themselves inside. The UN says that roughly 10,000 people have sought refuge at the two UN compounds there, according to CNN, and hospitals are straining to deal with an influx of patients.