Mutinous soldiers have opened fire in three big cities in Ivory Coast, defying a government order to lay down their weapons.
Gunfire has been heard near the presidential palace in the main city, Abidjan, the second city, Bouaké, and Daloa in the cocoa-growing west.
Pro-government forces are heading for Bouake, the epicentre of the mutiny.
The mutineers, who helped the president take office in 2011, have been locked in a pay dispute with the government.
The former rebels make up about 8,400 of the Ivory Coast’s 22,000-strong army.
Armed forces’ chief of staff General Sékou Touré has vowed to end the mutiny.
In a statement on Sunday, Gen Touré said that many of the mutinous soldiers had listened to earlier calls for them to stand down.
But an operation to end the mutiny had been launched because some soldiers were continuing to disobey orders, he added.
The mutineers have vowed to fight back if loyalist troops intervene.
Fears of a military standoff : Tamasin Ford, BBC News, Abidjan
This is all about the former rebels, now integrated into the army, who fought for years to bring President Alassane Ouattara to power. They brought Ivory Coast to a standstill in January when they launched uprisings across the country claiming they were due back pay and bonuses from that time.
The government gave in to their demands, promising them $15,500 each. It has paid them $6,500, but not the remaining $9,500, which had been promised at the end of May.
Then in a surprise move on national television on Thursday night, a spokesman for the former rebels apologised, dropping their demands for the rest of the money.
This was clearly news to the protesting soldiers. It is not clear why their spokesman dropped the demand but we know the government is struggling financially. With both sides saying they are not prepared to negotiate, there are fears of a military standoff.
Mutineers at the army headquarters in Abidjan’s financial district, near the presidential palace, have been shooting in the air, forcing schools and offices to remain closed, the BBC’s Tamasin Ford reports from the city.
Gunfire was also heard at the Akouédo barracks, in a suburb where many middle-class Ivorians and expats live, she says.
The mutinous soldiers spilled out on to the roads, causing panic, our reporter adds.
Sustained gunfire also broke out at the entrance and centre of Bouaké, which for many years was the main rebel-held city.
One person was killed by a stray bullet on Sunday after mutinous troops seized control of Bouaké
Cocoa businesses, banks and government buildings are shut in Daloa, Reuters news agency reports.
“The soldiers are in the streets on foot and on motorbikes. They’re shooting in the air,” it quoted resident Aka Marcel as saying.
It is unclear what impact the unrest will have on the cocoa industry.
Ivory Coast is the world’s biggest cocoa producer, and it is the West African state’s main foreign currency earner.
The government is already running short of money because of plummeting cocoa prices, making it difficult for it to meet the demands of the mutineers, our reporter says.
The mutiny has raised fears of a resurgence of the violence seen during Ivory Coast’s 10-year civil war, which ended in 2011.
Pro-Ouattara forces from Bouaké swept into Abidjan at the time, helping Mr Ouattara take office after his predecessor Laurent Gbagbo refused to accept defeat in elections.
Many of the rebels were rewarded for their backing by being given jobs in the army.