More than 1 million children have now fled South Sudan to escape the brutal conflict that erupted there just three-and-a-half years ago, the United Nations announced Monday.

Nearly one child out of every five has been displaced by the cycle of violence and unrest that has plagued much of the young country’s history.

South Sudan, the world’s newest nation, collapsed into civil war amid explosive political tensions in late 2013, just two-and-a-half years after gaining independence from Sudan. Its residents are also grappling with a dire food crisis as famine spreads through parts of the country.

One million of South Sudan’s 12.3 million people linger on the brink of famine, according to the U.N. And at least 100,000 are facing starvation.

Peace efforts have continued to crumble in the face of renewed intermittent clashes between the Sudan People’s Liberation Army, backing President Salva Kiir’s regime, and opposition forces loyal to former First Vice-President Riek Machar.

The crisis escalated drastically last summer, pushing people at a staggering rate of up to 3,000 per day into neighboring countries including Uganda, which is still rebuilding after its own deadly civil war and decades-long insurgency.

As the conflict worsens, the government has repeatedly thwarted humanitarian efforts by blocking and even expelling aid workers. The U.N.’s refugee agency, UNHCR, also released a report in March that accuses government forces and affiliated militia of using “the cover of an ongoing conflict to act as a ‘smoke screen’” while carrying out acts of civilian abuse with impunity.

Courtesy of UNICEF Nearly one-in-five South Sudanese children have been displaced by the conflict.

South Sudan’s one millionth refugee fled the country in September 2016. Less than eight months later, that number has nearly doubled, with children accounting for 62 percent of all South Sudanese refugees.

Tens of thousands of refugee children have been separated from their families, and an additional 1.14 million South Sudanese children are internally displaced.

This rapid mass exodus underscores the severity of the crisis, according to Leila Pakkala, UNICEF’s regional director for Eastern and Southern Africa. “The future of a generation is truly on the brink,” she warned.

Of the children who have remained inside the landlocked nation, more than one thousand have been injured or killed, and nearly three-in-four are not attending school ― the highest proportion of out-of-school children worldwide, the U.N. notes. They are also especially vulnerable to recruitment by armed forces, sexual abuse and exploitation, as well as emotional and psychological trauma.

“No refugee crisis today worries me more than South Sudan,” said Valentin Tapsoba, Africa Bureau director of UNHCR. “That refugee children are becoming the defining face of this emergency is incredibly troubling. We, all in the humanitarian community, need most urgent, committed and sustainable support to be able to save their lives.”

UNICEF has raised just 52 percent of its $181 million funding goal to support South Sudanese refugees this year. To help, you can donate here.