Rebels seized control of the capital of Central African Republic on Sunday, according to government officials.
Authorities said the takeover of Bangui had forced President Francois Bozize to flee to the Democratic Republic of Congo.
The Seleka rebel coalition resumed hostilities during the past week in the mineral-rich former French colony, vowing to oust Bozize.
The coalition accuses him of breaking a January peace agreement to integrate its fighters into the army.
Bozize seized power in a 2003 military coup.
The rebels fought their way to the northern suburbs of Bangui late on Saturday before an overnight lull in fighting. Heavy weapons fire then erupted early on Sunday morning, according to residents.
At least six South African soldiers are said to have been killed in the latest clashes.
As the rebels tightened their grip on Bangui, it was unclear who would replace Bozize. It was also unclear whether the country’s power-sharing government would remain in place.
Meanwhile, France said on Sunday that it had no plans to send more troops to the Central African Republic following the rebel takeover of the capital.
The French Foreign Ministry urged its citizens in the country to keep movements to a minimum.