U.N. officials say six humanitarian aid workers were ambushed and killed in South Sudan.
The officials said the workers were killed Saturday as they traveled in a convoy from the capital, Juba, to the the eastern town of Pibor.
"I am appalled and outraged by the heinous murder...," Eugene Owusu, the top U.N. humanitarian official in South Sudan said. "At a time when humanitarian needs have reached unprecedented levels, it is entirely unacceptable that those who are trying to help are being attacked and killed."
The U.N. says the killings represent the highest number of aid workers killed in a single incident since the country's civil war began in December 2013. Twelve aid workers have been killed this year in South Sudan and 79 have been killed since the civil war began.
The U.N. refugee agency reports 1.6 million South Sudanese have fled to neighboring countries to escape famine, fighting and drought, making South Sudan the world’s fastest-growing refugee crisis.
The U.N. refugee agency calls the rate of displacement from South Sudan alarming, placing an impossible burden on the region.
South Sudan’s civil war has displaced more than 3.5 million people both inside and outside the country. The United Nations reports 4.8 million people inside the country are going hungry, with 100,000 facing famine.