The United States safely evacuated American citizens on Sunday morning from Bor, South Sudan, where violence has been escalating over the past week.

United Nations and U.S. civilian helicopters evacuated Americans and citizens from “partner nations” to South Sudan’s capital of Juba, the State Department said. The evacuation occurred in consultation with the South Sudanese government.

"The United States and the United Nations, which has the lead for securing Bor airport in South Sudan, took steps to ensure fighting factions were aware these flights were a humanitarian mission," said State Department spokeswoman Jen Psaki in a statement.

On Saturday, the United States aborted an evacuation mission after three U.S. aircraft came under fire during a failed airlift, according to NBC News. Four U.S. troops were injured in the attack.

The deadly violence started about a week ago, after a failed coup, according to USA Today. South Sudan’s President Salvak Kiir blamed the attempted coup on rebels angry over the dismissal of the country’s former vice president, Riek Machar, in July.

So far, about 380 Americans and 300 citizens of other nations have recently been evacuated from South Sudan on four chartered flights and five military aircraft, Psaki said.

World leaders fear the violence could escalate to civil war in the country’s newest nation.