Looters and armed gangs roamed the streets of the Central African Republic capital Bangui after rebels seized control of the city on Sunday and the coup-prone country's president disappeared.
The fighters from the Seleka rebel coalition fought running battles with government troops before capturing the presidential palace and declaring victory.
They had resumed hostilities this week in the former French colony and moved rapidly south towards Bangui with the aim of ousting President Francois Bozize, whom they accuse of reneging on promises made in a January peace deal.
A high-ranking military source confirmed that Bangui was in rebel hands: "What is certain is that they have taken the city."
Homes, shops, restaurants and offices -- including the premises of the UN children's agency UNICEF -- were looted as armed men roamed the city where electricity supplies have been cut off.
"They break down the doors and loot and then, afterwards, the people come and help themselves too," said Nicaise Kabissou, who lives in a central district.
"There's looting all over town," said a diplomat in the city of around half a million residents that lies just north of the equator in the mineral-rich heart of Africa.
South Africa troops in Bangui -- who number around 250 and were supporting government forces -- suffered casualties in clashes with rebels, Brigadier General Xolani Mabanga told the SAPA news agency, but he was unable to provide any figures.
The International Committee of the Red Cross said injured people were flooding hospitals and medical centres in Bangui, and asked for secure access to the capital.
The whereabouts of Bozize, who seized power in a coup in 2003, remained a mystery.
A well-placed source told AFP he had left the country in a helicopter, but did not disclose his destination, while French Foreign Minister Laurent Fabius confirmed only that he had fled Bangui.
Officials from neighbouring Democratic Republic of Congo and Congo-Brazzaville said he was not on their soil, although it would be easy to cross the river Ubangui to reach the DR Congo.
A security source in Kinshasa said 25 members of Bozize's family had made that short trip to seek refuge in the Congolese town of Zongo.
But he could not say whether Bozize himself was also there.
-- Reports of human rights abuses --
French President Francois Hollande called on all parties in the conflict to form a government in accordance with the peace deal reached in January, and asked "the armed groups to respect the population".
That call was echoed by the United States, which also expressed deep concern over "widespread reports of human rights abuses" by both national security forces and rebels.
As the rebel forces arrived at the outskirts of the capital on Saturday, France called for an emergency meeting of the UN Security Council to discuss the deteriorating situation.
It has sent an extra 300 French troops to back up the 250 soldiers already there to protect an estimated 1,250 French nationals living in the landlocked country, the military said in Paris.
The January peace deal made opposition figure Nicolas Tiangaye the head of a national unity government that was due to carry out reforms before elections next year.
US State Department spokeswoman Victoria Nuland on Sunday urged the rebels "to provide full support to Prime Minister Tiangaye and his government" and to uphold the January peace deal.
The deal also brought several prominent figures from Seleka, a loose alliance of three rebel movements, into the government.
But it collapsed after the rebels said their demands, which included the release of people they described as political prisoners, had not been met.
Seleka first launched its offensive in the north on December 10, accusing Bozize of not abiding by the terms of previous peace agreements.
Facing little resistance from the badly trained and ill-equipped army, they seized a string of towns, defying UN calls to stop before halting within striking distance of Bangui.
Negotiations brought an end to that offensive and led to the January peace deal reached in Libreville.
Colonel Djouma Narkoyo, a rebel commander on the ground, said Saturday the rebels were ready to meet with regional African leaders on the crisis but refused to negotiate with Bozize.
Bozize's legacy after a decade in power is a country riddled with corruption and mired in poverty, despite abundant natural resources such as uranium, gold, oil and diamonds.
The state, which has a population of about 4.5 million, has been unstable since independence from France in 1960.
It endured a notoriously brutal period under self-declared emperor Jean-Bedel Bokassa, who was overthrown in 1979 in a French-backed coup.