The brutal conflict, sparking UN warnings over ethnic cleansing, is driving a devastating famine that is threatening millions with starvation in the country, reported the Independent.
One woman, who fled violence in the city of Yei, told how she saw her best friend and her children, including three-month-old baby, butchered.
“The children and the elderly, they slaughtered them,” Sylvia, 31, told Save the Children aid workers.
“When the armed groups get you with your children, they will kill all of you.
“They will take you from your homes and slit your throat. For the small children they stab them, then they die later.
“I've seen children tied to their dead mother and thrown in the river — soldiers have been doing this a lot.”
Sylvia fled after seeing her best friend murdered, taking in a baby girl she found abandoned at the roadside on her journey to neighboring Uganda.
“When we began our journey, I saw with my own eyes two boys and one woman…they had been slaughtered,” she added, saying soldiers were using knives to save bullets.
“Children weren’t going to school, there was hunger everywhere. Children would die of illness.”
A famine was declared in parts of South Sudan last month in the first such catastrophe the world has seen in six years.
More than 5.5 million people — almost half the population — will not have a reliable source of food by July in what the UN says is a worsening man-made crisis, driven by the conflict and worsened by government inaction.
The world's youngest nation has been mired in civil war since 2013, when President Salva Kiir fired his deputy Riek Machar, sparking a war that has increasingly split the country along ethnic lines.
Fighting, massacres, looting and village burning has killed tens of thousands, caused widespread hunger and forced three million people from their homes — pitting Kiir's Dinka ethnic group against Machar's Nuer.
A report presented to the UN Human Rights Council in Geneva concluded that both government forces and non-state groups were targeting civilian populations on the basis of their ethnic identity with killings, abductions, gang rape and sexual violence on an 'epic' scale.
A UN survey found 70 percent of women living in 'protection of civilian camps' in the South Sudanese capital of Juba had been raped, the vast majority by police or soldiers, while a staggering 80 percent had been forced to watch someone else being assaulted.
Thousands of refugees are pouring over the border every day into Uganda, where more than 500,000 people have arrived since last July, with almost 90 percent women and children.