Dozens of people have been killed by clashes in South Sudan’s capital Juba, military, medical and journalistic sources have said.
Gunfire broke out on Friday evening near the state house where President Salva Kiir was meeting his sometime rival, Vice-President Riek Machar.
Estimates of the death toll vary, but most accounts put the number over 100 – some as high as 150.
A 2015 peace deal to end a 20-month civil war has failed to quell unrest.
Juba is in lockdown as South Sudan, the world’s newest country, marks the fifth anniversary of independence from neighbouring Sudan.
Friday’s fighting was apparently sparked by a shootout between Mr Kiir’s bodyguards and Mr Machar’s. The two men met at the presidential palace on Friday.
The half-hour gun battle then escalated, with heavy weapons and artillery being used in several parts of the city.
On Saturday, a South Sudanese journalist told the BBC that other journalists stuck inside the state house counted at least 100 bodies, inside and outside the compound.
A hospital doctor told the Associated Press that scores of bodies had been brought in, while a military spokesman for the opposition – Mr Machar’s faction – told Reuters 115 people had been killed.
Mr Kiir and Mr Machar described Friday’s violence as “unfortunate”.
Under a peace deal agreed last August, the two armed factions took up positions in Juba in April.
Tens of thousands died in the civil war and millions were forced from their homes.
South Sudan, the world’s youngest nation, is so broke that the authorities say no official anniversary celebrations will be held.
The streets of Juba were reported to be fairly quiet on Saturday.
Roadblocks have been set up in the capital, with troops searching people for weapons.