Deadly fighting erupted, with civilians killed along ethnic lines and thousands displaced in clashes Monday between government forces and rebels in South Sudan's second-largest city of Wau, witnesses and priests said.
At least 2,000 people sought shelter in a Catholic church, and many reported targeted killings against civilians by government troops, according to local priest Moses Peter.
Wau is located in a region that has repeatedly changed hands between government troops and rebels loyal to former vice president Riek Machar since the country descended into civil war in 2013. The town itself is held by government forces.
"The (people) who came are reporting to us that there are SPLA soldiers in the residential areas," priest Moses Peter said, using an acronym for the national army.
"They are shooting and are targeting certain groups of people and they are even looting houses."
Local resident Tibur Erynio, 41, said a tally of the dead from his neighbours stood at 18, most of them from minority ethnic groups the Jur and Balanda.
The civilians were "killed because they are suspected of supporting rebels," said Erynio, adding that this was not true.
Erynio said shops and markets in the city's southern half were closed and the government had told people to stay indoors.
"You can only see people are moving, running either to the church for protection" or to a UN peacekeeping compound, he said.
One local resident, who asked not to be named, told AFP he had found his brother "lying in blood after he was shot", and had counted five other dead bodies.
Another, who gave her name as Mary Joseph said: "we saw three people lying dead in different places."
Military spokesman Colonel Santo Domic Chol said the fighting started over the weekend as government troops were trying to rout rebels from areas of the countryside they controlled.
The skirmishes reached Wau town on Monday, where Domic said forces loyal to Machar took cover among civilians.
Four prison guards were killed in the fighting, Domic said, without elaborating.
South Sudan descended into violence more than three years ago after a power struggle between Machar and President Salva Kiir.
Much of the fighting has broken down along ethnic lines and has persisted despite an August 2015 peace deal intended to end the war.
At least 1.7 million people have fled the country because of the war, and 1.9 million are internally displaced.
In February, the government declared a famine in parts of the country badly affected by the fighting.
The violence in Wau came days after the government's top general Paul Malong visited the city in a trip billed as a morale-booster for front-line troops.
