From this Reuters story that we found at The New York Times, we learn more details about the attacks.
About 40 southern Sudanese soldiers and civilians were killed when tribal fighters ambushed boats carrying food aid, the latest in a string of ethnic attacks threatening a fragile peace deal, officials said Sunday.
Members of the Jikany Nuer group opened fire Friday on 27 boats loaded with emergency rations destined for an area controlled by the rival Lou Nuer tribe, the United Nations World Food Program said.
Hundreds have been killed and more than 135,000 displaced in southern Sudan this year in tribal killings. The violence is rooted in longstanding feuds over cattle, aggravated by political discontent and weapons left over from two decades of civil war.
A United Nations official said the attack on Friday was thought to be the first in which southern Sudanese soldiers had suffered significant casualties in the tribal clashes.
The minister of information for Upper Nile State, Thon Mom, said the attack killed at least 40 people, including troops from the Sudan People’s Liberation Army, the former rebel group based in southern Sudan. The troops were escorting the convoy south on the Sobat River to the town of Akobo.
“Women and children who were on the boats were also killed, either directly by bullets or by drowning after jumping into the river,” said Malaak Ayuen Ajok, an army spokesman.
He said the Jikany Nuer fighters had demanded to search some of the barges, south of the settlement of Nasir, suspecting they were carrying arms and ammunition to the Lou Nuer.
They searched one barge, finding only sorghum and other rations, but opened fire when the rest of the convoy continued on its journey, he added.
The officials said they were awaiting more detailed information on the attack. “It could be less than 40 killed,” Mr. Ajok said. “It could be more. We should find out later today.”