Civil war in South Sudan, erupting two years after the country won independence from Sudan and fought largely along ethnic lines between Dinkas and Nuers, caused hundreds of thousands of deaths between 2013 and 2018.
The shooting happened on Tuesday when the commissioner of Boma County in Pibor was returning from a visit to a village.
"The commissioner with his team went to Nyat village and on his return, he was ambushed and 15 people were killed including the commissioner," Abraham Kelang, information minister of Greater Pibor Administrative Area, said.
The attackers were suspected to be youths from the region's Anyuak community, Kelang added.
Among the dead were Boma's deputy army commander, government officials and the county commissioner’s bodyguards, the information minister said.
Since the 2018 peace deal, routine clashes among a patchwork of armed groups have continued to kill and displace large numbers of civilians. The Greater Pibor Administrative Area is among those affected.
Inhabited mostly by the Murle ethnic community, Boma County has experienced periodic violence sometimes between the Murle and Anyuak or with the Nuer or the Dinkas from neighboring Jonglei State.
The violence is also motivated by cattle rustling.