A severe food shortage has deteriorated into a famine in two counties in South Sudan, the government and United Nations announced Monday, with 100,000 people facing starvation.

Joyce Luma, head of the World Food Program in South Sudan, called the famine “man-made,” blaming it on political turmoil in a country engulfed in civil war since late 2013.

Luma and representatives of two other U.N. agencies — UNICEF and the Food and Agriculture Organization (FAO) — issued the famine declaration at a news conference in Juba, South Sudan’s capital, along with Isaiah Chol Aruai, the head of the country’s National Bureau of Statistics. A formal declaration of famine indicates that people are dying of hunger.

“Our worst fears have been realized. Many families have exhausted every means they have to survive,” said Serge Tissot, representative of the FAO in South Sudan.

The agencies painted a grim picture of the situation in the impoverished country, saying that 100,000 people are at risk of starvation and that 1 million more are on the brink of famine.

About 5.5 million people, or about half of South Sudan’s population, will face severe food shortages by the summer unless more relief is provided, they said.

South Sudan, which became independent from Sudan in 2011 with strong support from the U.S. government and the international community, descended into conflict in December 2013, when President Salva Kiir fired his vice president, Riek Machar. The ensuing war took on ethnic overtones, with Kiir’s Dinka group battling members of Machar’s Nuer group.

Tens of thousands of people have died and more than 1.5 million have fled the country.

The U.N. officials said that war had disrupted agriculture, the main occupation in many parts of the country, crippling the economy and leaving people unable to feed themselves. People were relying on “whatever plants they can find and fish they can catch,” Tissot said. The two counties affected by famine are in Unity state, an important oil-producing state in the north.