WASHINGTON — (CNN) The United States and India are evacuating nonemergency staff from their missions in South Sudan as bloody violence in the capital spirals, leaving scores of people dead, including two Chinese U.N. peacekeepers.

Following an overnight lull, fighting resumed Monday morning, with the sound of gunfire blasting through parts of the capital, Juba, according to Shantal Persaud, acting spokeswoman for the U.N. Mission in South Sudan.

On state-run television Monday, South Sudanese President Salva Kiir demanded an immediate end to the fighting between his Sudan People’s Liberation Army and the Sudan People’s Liberation Army in Opposition.

Fighting first broke out Thursday in the world’s newest formed nation, with skirmishes between troops loyal to Kiir and soldiers backing his rival, Vice President Riek Machar.

Violence flared again Sunday and Monday after a halt the day before when the country celebrated the fifth anniversary of its independence from Sudan.

“What we may be seeing is a total breakdown of command and control in Juba,” said Kate Almquist Knopf, director of the Africa Center for Strategic Studies. “We need to watch carefully for whether a cycle of reprisal killings by either side begins in the next few days.”

The International Committee of the Red Cross said it ceased almost all its operations in Juba on Friday afternoon due to fighting.

Persaud, the U.N. mission spokeswoman, talked to CNN by phone from a U.N. compound, taking cover in the bathroom as gunfire was exchanged outside the complex near Jubal’s airport.

Shots were also heard outside a U.N. civilian protection facility in the city’s southeast.

The U.N. Security Council, which held a closed door meeting Sunday, expressed “shock and outrage” at attacks on civilians and U.N. compounds, saying they may constitute war crimes.

It called on Kiir and Machar to control their respective warring forces, prevent the spread of violence and commit themselves to implementing a ceasefire and peace agreement.

Machar said that soldiers on his side had been bombarded from helicopters.

An estimated 83,000 people are seeking refuge in churches, schools and outside the peacekeeping base of the U.N. mission, according to the United Nations.

Humanitarian workers have been stopped and threatened at checkpoints when trying to deliver assistance, unable to reach the most needy, according to Chaloka Beyani, the U.N. special rapporteur on the human rights of internally displaced persons.

International law requires that parties in conflict allow humanitarian workers to have safe passage, he said.

The threats to humanitarians in the western city of Wau are unconscionable, his office said in a statement Monday, stressing that leaders of armed groups and forces must tell their troops to back off.

Two weeks ago, fighting in Wau displaced at least 70,000, according to the United Nations.

“I am deeply disturbed by the renewed outbreak of violence in South Sudan, a country which marked its fifth anniversary of independence on Saturday with gunfire instead of celebration,” Beyani said.

“Everything came to a halt because there was too much confusion, too much shooting, too much commotion in town. Checkpoints are making movements impossible,” said Jurg Eglin, head of the Red Cross mission in the country.

Thousands of people took shelter at the World Food Programme’s compound, also close to the fighting, said Challis McDonough, the organization’s senior regional spokeswoman.

The compound “is designed for about 100 people and it’s got something like 3,000 in it right now,” McDonough said.

She said the fighting might hinder distribution of food with the country’s main center of coordination in lockdown.

“The humanitarian needs are acute in some parts of the country, and we are trying to make sure we can continue that support, but we need to make sure it is in a way that is as safe as possible for our staff and partners,” she said.

A Kenyan nongovernmental organization worker trapped in a hotel talked to CNN online. CNN is not able to provide his name because he is not authorized to speak to media.

“We are stranded in hotels,” he said. “All we can hear is the fighting outside. There is a perennial lack of supplies, food, water, fuel for the generators, and all we know is that the airport is closed and we cannot access it to fly out. The roads are being manned by soldiers who are robbing and harassing anyone who dares approach them.”

“We keep thinking the fighting has stopped,” he continued, “but even after two hours of calm, it is followed by hours of gunfire and shelling.”

“Kenyans who are stuck here are ready to pay for their bus and air tickets out of Juba but the border is closed and airlines have canceled flights. The only way out is if fighting reduces.”

The U.S. State Department said the security situation in Juba on Sunday had seen a “sudden and serious deterioration,” with clashes between government and opposition forces breaking out into “general fighting.”

Indian External Affairs Minister Sushma Swaraj said in a tweet that Indian nationals were being evacuated and warned others not to travel to the country.

There are many Indian nationals working at the U.N mission there.

Koro Bessho, Japan’s ambassador to the United Nations, confirmed the death of a Chinese soldier, while Chinese state broadcaster CCTV reported the death of a second Chinese peacekeeper.

Other Chinese and Rwandan peacekeepers also sustained injuries.

How many have been killed in fighting between the factions is unclear.

One estimate puts the death toll close to 150, while other reports indicate more than 270 have been killed.

CNN is working to confirm an exact death toll.

Gunfire from “heavy weaponry” was exchanged for much of Sunday outside a U.N. building on the outskirts of Juba, the U.N. mission to the country said.

The mission sent out a series of tweets at about 8:25 a.m. (1:25 a.m. ET) describing “gunshots” and a “heavily armed exchange” outside a U.N. compound.

The U.S. Embassy issued an alert saying that fighting between government and opposition forces was ongoing at the U.N. mission’s headquarters, the Jebel area of the city and near the airport.

The U.N. mission said that 1,000 internally displaced people had fled its protection as violence hit areas near their camps.

“Both UNMISS compounds in Juba have sustained impacts from small arms and heavy weapons fire.

“The United Nations urges all parties to respect the sanctity of the United Nations and condemns any deliberate targeting of United Nations premises and its personnel,” it said in a statement.

Kenya Airways, which operates two flights a day to Juba, said it was suspending all flights to the city because of an “uncertain security situation,” while Britain’s Foreign Office advised against all travel to South Sudan, saying “the security situation in Juba has deteriorated” since Friday.

Rwanda Air and Fly 540 also said they were suspending flights into Juba.

The country is nearly out of money because its funds come almost exclusively from oil revenue — the value of which has plummeted.

People have become desperate. In lieu of payment, government soldiers have reportedly been allowed to rape women, a U.N. report said.

South Sudan gained independence in 2011 after 98% of the population voted to break away from Sudan.

The East African nation, the youngest country in the world, quickly fell into civil war that took on ethnic undertones.

In December 2013, soldiers from Kiir’s Dinka ethnic group tried to disarm Nuer soldiers perceived to be loyal to Machar.

Soldiers targeted Nuer civilians in the ensuing fighting, Human Rights Watch said.

At least 50,000 were killed and more than 2 million displaced in the civil war, and nearly 5 million people faced severe food shortages.

Under a peace deal signed in August, Kiir became the president of the country, and Machar the first vice president.