At least 272 people have died in fighting between South Sudan's rival factions in the capital Juba, including 33 civilians, a government source said on Sunday, as heavy gunfire erupted again in the city and many residents sought shelter at a UN base.
The renewed violence has sparked fears that South Sudan could be sliding back into conflict after recently emerging from a two-year civil war – which began in December 2013, when President Salva Kiir fired vice president Riek Machar.
The latest bout of fighting first broke out on Thursday and Friday between troops loyal to Kiir and soldiers who support Machar.
A spokesperson for Machar told the BBC that South Sudan was "back to war."
Neighboring Kenya called for urgent action by the two leaders to move troops away from civilians and end the crisis.
On Saturday Juba had been calm, but on Sunday a witness and residents who spoke to Reuters said gunfire was heard in suburbs outside Juba, near the military barracks that hosts troops loyal to Machar.
"For about 30 to 40 minutes we heard sounds of heavy artillery in the direction of Jebel area," an aid worker based in Juba who did not want to be named told Reuters.
One resident, Daniel Samson, said he had seen a "massive migration" of people fleeing to calmer districts when there was a lull. "The gun shooting has stopped now," he said.
Another resident, who only gave his name as Steven, said he had seen hundreds heading to a UN compound. "I saw dead bodies of civilians and others … moving with blood on their bodies," he told Reuters by telephone.
One eyewitness saw soldiers apparently involved in looting, by entering a neighbor's shop and leaving with merchandise. It was not clear if those troops supported Kiir or Machar.
South Sudan's civil war was fought largely along ethnic lines with Kiir, a Dinka, and Machar, a Nuer, drawing support from their respective tribes.
A peace agreement last August ended the war but Kiir and Machar spent months after that wrangling over details and have yet to integrate their forces, a key part of the peace deal.