text: United Nations officials rarely use the words "genocide" and "ethnic cleansing," but they now say potentially both could envelop the world's youngest country.
  Since violence flared in Juba in July and spread to the previously peaceful southern Equatoria states of South Sudan, 340,000 people have fled the violence into neighbouring Uganda.
  That is more than any other country this year - the UN says 200,000 people have fled Syria in 2016.
  Every day, on average, another 2,500 South Sudanese become refugees, and the stories of what they escaped and what they saw on the way, add to the evidence of killing, rape and the targeting of civilians along ethnic lines.
  Nelson Ladu Thomas has twice walked over the small wooden bridge dividing South Sudan and Uganda at an unofficial border crossing known as Busia.
  A trickle of a stream divides these two countries and there are small bridges or fallen trees every couple of kilometres.
  The first time he crossed was with his immediate family; the second - a day later - was with his brother's wife and her five children who he had gone back to help.
  Six-year-old Moriswani was limping up the hill to the Ugandan police post where their possessions were inspected before being allowed on to a reception centre a little further up the road.
  I asked him what they had left behind.
  "They are killing people, sleeping with wives, stealing. They are not shooting you, they are cutting you with a knife. Even small children can be beaten down," Mr Thomas told me.
  The children gulped water and sat exhausted in the shade of a harsh sun.
  "They don't want us," he said, and gave his explanation of why his town of Yei, just 80km (50 miles) from the border, had become a place he had to leave.
  "These tribes of Dinka, they don't want Equatorians, they don't want… Nuer. They don't want them."
  Ethnic violence has dominated the crisis in South Sudan.
  The civil war began as a dispute between the Dinka President Salva Kiir, and former Vice-President Riek Machar who is Nuer.
  Equatorians only started to be targeted in July, when the violence spread to their part of the country after rebel troops fled the capital.
  In a long line of people at a nearby refugee reception centre, Otima Amos, 21, explained how he had crossed the border after walking through the bush for many days with 16 other people - most children, and among them two-year-old twins."We walked up to here - without any other form of transport," he said.
  "It was very hard because they were killing people. If you were a boy you would be killed, if you were a girl or a woman they would just rape you. If not, you would be killed."
  They were afraid they would be caught as they tried to escape.
  Uganda is coping extremely well with the huge influx of refugees.
  With the help of aid agencies, within 36 hours each family is allocated a 30m square patch of land and a tarpaulin to set up a shelter and start planting crops.
  Faida Sarah arrived in August with her children, but already has okra ready to harvest as well as onions, tomatoes and greens bursting out of the ground.
  The reason she left Yei was because one night soldiers came round to her home, demanded car keys from her husband and then hacked him to death just outside the house.
  In July Bidi Bidi was a village, but now it is one of the biggest refugee settlements in the world - home to more than a quarter of a million people and covering 250 square kilometres.
  But now home to nearly a million refugees, Uganda is beginning to struggle with its generous approach.
  "This has been unrelenting since July," said Nasir Abel Fernandes, the UNHCR's senior emergency coordinator in northern Uganda.
  "The international community has to pay attention, and pressure the South Sudanese leaders to stop this, as it's a massacre of civilians from both sides."
  He says supplying water to the refugees is a problem, as it has to be trucked in.
  As many as half the refugees are children, and schools are already running - exams were being marked and a presentation prepared for our visit.
  Girls sang and danced in a circle then Patricia Mercy, 16, stepped forward with confidence to deliver her poem.
  "War, war, war," she began, "who are you and where do you come from?"
  The confidence and resilience of her performance hiding deep trauma.
  "You have killed my mother and father, even my brothers and sisters, leaving me to be called an orphan."
  There are so many terrible stories here of what South Sudan is doing to its own people.
  Read more:
  'I spent days hiding in a swamp'
  Artists paint for peace
  Uganda: 'One of the best places to be a refugee'
target: For three years South Sudan has tumbled deeper into self-inflicted chaos, and it now finds itself on the brink of something even more terrifying.