Embassies and aid organizations in South Sudan were trying to evacuate staff from the capital, Juba, on Tuesday as a precarious calm settled over the city following several days of deadly clashes.

Hundreds have been killed in the fighting that began Thursday night. South Sudan’s government has said at least 272 were killed, including 33 civilians.

President Salva Kiir and former rebel leader, First Vice President Riek Machar, declared separate cease-fires Monday night. The cease-fires appear to have held so far.

Military trucks are driving up and down Juba’s roads with megaphones ordering soldiers back to barracks.

Japan has urged dozens of its nationals including aid workers in Juba to leave the country and dispatched military aircraft to evacuate them following the fighting. The U.S. Embassy, Doctors Without Borders and the International Medical Corps are among organizations pulling out their staffs from South Sudan. Private chartered planes flew foreigners out of Juba’s reopened airport Tuesday, as regional carriers including Kenya Airways had cancelled flights there.

Neighboring Uganda will send troops to Juba to evacuate its citizens, said Ugandan army spokesman Paddy Ankunda.

The fighting in Juba severely threatened a peace deal signed last year between Kiir and Machar that brought them and their supporters into a transitional coalition government in April.

It is “hugely worrying” that the fighting appeared to be spreading outside South Sudan’s capital, the U.N. human rights office in Geneva said on Tuesday.

Government troops lined up tanks and fired on a U.N. base where tens of thousands of civilians are sheltering, according to witnesses. At least eight civilians in the U.N. camp were killed in the crossfire. Two Chinese peacekeepers with the U.N. mission were also killed.

Government officials have repeatedly accused the civilians inside the U.N. bases of being rebels or rebel supporters.

However, South Sudanese nationals trying to escape the capital were prevented from doing so by authorities, according to a security worker in Juba who insisted on anonymity because he is not authorized to speak to the press.

Aid groups are warning about the lack of clean water for the tens of thousands of people sheltering in various sites around Juba as water tankers have not been able to make deliveries.

Kiir and Machar fought a civil war against each other since late 2013 which killed tens of thousands of people. That war exposed deep ethnic fault lines, pitting the Dinka supporters of Kiir against the Nuer followers of Machar.

In recent days, the government overran one of Machar’s two bases in Juba, deploying helicopter gunships and tanks against opposition forces carrying only light arms. Some 35 of Machar’s bodyguards were killed in the latest clashes, said opposition military spokesman William Gatjiath.

The latest fighting has awakened fears that South Sudan’s other ethnic groups will be drawn in.