Five United Nations peacekeepers from India and 7 civilians were shot dead during an attack on a convoy in South Sudan, officials said.

South Sudan military spokesman Col. Philip Aguer said the attack took place on a convoy traveling between the South Sudanese towns of Pibor and Bor on Tuesday morning. Aguer blamed the attack on militants led by David Yau Yau, a rebel leader that South Sudan says is armed by Sudan.

The top U.N. envoy in South Sudan, Hilde Johnson, said in a statement that five peacekeepers and seven civilians working with the U.N. mission were killed. She said at least nine additional peacekeepers and civilians were injured and some remain unaccounted for.

Syed Akbaruddin, spokesman of India's Ministry of External Affairs in New Delhi, India, said the convoy, which included 32 Indian soldiers, was attacked by rebels in Gurmukh in the volatile state of Jonglei. He said the casualties are being brought to the capital of South Sudan, Juba, and the injured will be sent to the U.N. mission hospital. The Indian embassy will work with the U.N. to bring the bodies back to India, he said.

India has about 2,200 Indian army personnel in South Sudan. They are in two battalions. One is based in Jonglei and the other is in Malakal, in the Upper Nile, on the border with Sudan.

The Indian embassy said it will inform families before releasing the names of the soldiers killed.

Johnson, sent condolences to the families of the dead and injured.

South Sudan ended decades of civil war with Sudan in 2005 and peacefully formed its own country in 2011. But the south is still plagued by internal violence and shaky relations with Sudan. Leaders in Khartoum, Sudan's capital, deny that they are arming Yau Yau.

The Associated Press contributed to this report.