Two Indian peacekeepers have died in an attack on a United Nations compound in South Sudan's Jonglei state, India's foreign ministry has said.
Rebels from the second-largest ethnic group, the Nuer, stormed the base on Thursday, targeting civilians of the majority Dinka ethnic community.
South Sudan has been in turmoil since President Salva Kiir accused his ex-deputy Riek Machar of mounting a coup.
The unrest, which broke out on Sunday, has killed some 500 people so far.
The conflict first erupted in the capital Juba but has since spread.
Mr Kiir, who is a Dinka, has blamed the violence on a group of soldiers who support Mr Machar, a Nuer.
The president accuses them of trying to take power by force on Sunday night in a coup attempt by Mr Machar - a claim the former vice president denies.'Growing violence'
Indian foreign ministry spokesman Syed Akbaruddin tweeted that Dharmendra Sangwan and Kumar Pal Singh had been killed in the attack on the UN compound, in the town of Akobo.
There were 43 Indian peacekeepers in total at the compound, India's UN envoy Asoke Mukerji said.
A UN spokesman said the attackers, mainly youths, had targeted 32 Dinka civilians who had sought refuge at the base.
Security at the compound has been increased.
The UN has expressed worry about a possible civil war between the Dinka and the Nuer.
UN Secretary-General Ban Ki-moon said he was "deeply concerned by reports of growing violence in many parts of South Sudan, human rights abuses and killings fuelled by ethnic tensions".
However, the government insists the clashes are over power and politics, noting that both sides involved in the clashes include leaders from different tribes.
"We condemn in strongest possible terms attempts to depict the coup as ethnic strife," a government statement said.
The UN is sheltering more than 30,000 civilians in five state capitals, including Juba and Bor.
Early on Thursday, Nuer rebels seized control of Bor. Even before the unrest, the town was seen as one of the most volatile areas of South Sudan.
In an interview with Radio France Internationale, Mr Machar called on the army to remove the president.
"We want him to leave, that's it," he told the station.
Mr Machar was sacked by Mr Kiir in July.
The UN has called for political dialogue to end the crisis, and the Ugandan government says its president has been asked by the UN to mediate between the two sides.
A delegation of East African foreign ministers earlier arrived in Juba to try to mediate in the crisis.
Britain and the US have both sent planes to airlift their nationals out of the country, and a US defence official described the situation as "getting ugly".
South Sudan has struggled to achieve a stable government since becoming independent in 2011.
The oil-rich country remains ethnically and politically divided, with many armed groups active.