UN mission in South Sudan evacuates non-critical staff amid attacks, escalating violence

FILE - In this June 7, 2007 file photo, a CV-22 Osprey aircraft stationed at Kirtland Air Force Base kicks up a cloud of dust as it touches down at the Grants/Milan Airport in Grants, New Mexico, USA. Gunfire hit three U.S. military CV-22 Osprey aircraft Saturday, Dec. 21, 2013 trying to evacuate American citizens in Bor, the capital of the remote region of Jonglei state in South Sudan, that on Saturday became a battle ground between South Sudan's military and renegade troops, officials said, with four U.S. service members wounded in the attack. (AP Photo/Gallup Independent, Matt Hinshaw, File) (The Associated Press)

In this photo taken Wednesday, Dec. 18, 2013 and released by the U.S. Air Force, soldiers of the East Africa Response Force (EARF), a Djibouti-based joint team assigned to Combined Joint Task Force-Horn of Africa, prepare to load onto a U.S. Air Force C-130 Hercules at Camp Lemonnier, Djibouti, to support with an ordered departure of personnel from Juba, South Sudan. Gunfire hit three U.S. military CV-22 Osprey aircraft Saturday, Dec. 21, 2013 trying to evacuate American citizens in Bor, the capital of the remote region of Jonglei state in South Sudan, that on Saturday became a battle ground between South Sudan's military and renegade troops, officials said, with four U.S. service members wounded in the attack. (AP Photo/U.S. Air Force, Tech. Sgt. Micah Theurich) (The Associated Press)

In this photo taken Wednesday, Dec. 18, 2013 and released by the U.S. Air Force, soldiers of the East Africa Response Force (EARF), a Djibouti-based joint team assigned to Combined Joint Task Force-Horn of Africa, depart from a U.S. Air Force C-130 Hercules in Juba, South Sudan to support with an ordered departure of personnel from the city. Gunfire hit three U.S. military CV-22 Osprey aircraft Saturday, Dec. 21, 2013 trying to evacuate American citizens in Bor, the capital of the remote region of Jonglei state in South Sudan, that on Saturday became a battle ground between South Sudan's military and renegade troops, officials said, with four U.S. service members wounded in the attack. (AP Photo/U.S. Air Force, Tech. Sgt. Micah Theurich) (The Associated Press)

The United Nations Mission in South Sudan says it is relocating all non-critical staff from the capital, Juba, to Uganda amid escalating violence as the country's military battles rebel forces.

The mission said in a Twitter update Sunday that all remaining civilian staff in Bor — the Jonglei state capital that has been the scene of fierce fighting — had been evacuated to Juba.

On Saturday gunfire hit three U.S. military aircraft trying to evacuate American citizens in Bor, wounding four U.S. service members in the same region gunfire downed a U.N. helicopter on Friday.

The latest violence in the world's newest country has killed hundreds and has world leaders concerned about war.

The U.N. chief Sunday urged South Sudan's leaders "to do everything in their power" to stop the violence.