[Updated at 3:36 p.m. ET] The South Sudanese armed forces admitted shooting down a United Nations helicopter in eastern South Sudan on Friday.

The Sudan People's Liberation Army said it was an accident, according to spokesman Philip Aguer.

Four crew members were killed, the United Nations Mission in South Sudan said. The group reported that there were no passengers on board.

Aguer said that a craft was seen about 9 a.m. hovering near an SPLA command area. The army asked the U.N. mission whether it had sent a plane.

"The U.N. said there is no plane, they don't have plane in the area," Aguer said.