One of the uprising's leaders said the soldiers were "ready to fight" if attacked.
Sergeant Seydou Koné said they did not want to negotiate with anyone, according to Reuters news agency.
The unrest began after a spokesman for the soldiers announced on Thursday that they had dropped their pay demands.
In January, they forced the government into paying them about $8,000 (£6,200) each in bonuses to end a rebellion. They were due to receive a further payment this month and about 8,000 mutineers are unhappy that they were not consulted ahead of Thursday's televised announcement.
Three former rebels from the country's civil war era were wounded on Saturday after the mutinous soldiers opened fire in Bouaké to stop them staging their own protest, Sergeant Koné said.
There have also been reports of injuries after shooting in the northern city of Korhogo.
The military chief of staff, General Sékou Touré, had threatened "severe disciplinary sanctions" on Friday if the uprising did not end. Shops are closed and soldiers are patrolling and firing in the air in Bouaké, residents said.
The mutineers have also taken control of the city of Odienne, in the north, reports say.
On Friday, shots were fired in the air at military bases in Abidjan, Bondoukou in the east, Bouaké in the centre, and Korhogo. It is believed the mutineers were firing blanks.
In response, elite Republican Guard troops in Abidjan fired warning shots that pushed the mutineers back inside the military headquarters compound in Abidjan, Reuters reported. The situation in the city on Saturday was said to be calm.
Reacting to the spreading unrest, President Alassane Ouattara held an emergency meeting of the country's security council.
The mutiny has raised fears of a resurgence of the violence seen during Ivory Coast's 10-year civil war, which ended in 2011.
Many of the mutineers in January were thought to be former rebels who joined the army after the conflict.
Angry soldiers have blocked off access to Bouaké, the second largest city in the Ivory Coast, as a revolt over a pay dispute continues.