What you need to know:
- Earlier, military officers said they had toppled Bongo, who has been in power for 14 years, hours after he had been declared the victor in Saturday's elections.
Rebel officers in Gabon announced Wednesday they had seized power following disputed elections in which President Ali Bongo Ondimba, whose family has ruled the oil-rich state for more than 55 years, had been declared winner.
The claimed takeover sparked condemnation from the African Union (AU) and alarm from Nigeria over "contagious autocracy" in a continent where the military have seized power in five other countries since 2020.
Bongo, 64, who took over from his father Omar in 2009, was placed under house arrest and one of his sons arrested for treason, the coup leaders said.
In a dramatic pre-dawn address, a group of officers declared "all the institutions of the republic" had been dissolved, the election results cancelled and the borders closed.
"Today, the country is going through a serious institutional, political, economic and social crisis," according to the statement read on state TV.
It was read by an officer flanked by a group of a dozen army colonels, members of the elite Republican Guard, regular soldiers and others.
The elections "did not meet the conditions for a transparent, credible and inclusive ballot so much hoped for by the people of Gabon," the statement said.
"Added to this is irresponsible and unpredictable governance, resulting in a continuing deterioration in social cohesion, with the risk of leading the country in chaos."
"We -- the Committee for the Transition and Restoration of Institutions (CTRI) on behalf of the people of Gabon and as guarantors of the institutions' protection -- have decided to defend peace by putting an end to the current regime," it said.
TV images later showed the head of the Republican Guard, General Brice Oligui Nguema, being carried in triumph by hundreds of soldiers, to cries of "Oligui president."
Bongo's son and close adviser Noureddin Bongo Valentin, his chief of staff Ian Ghislain Ngoulou as well as his deputy, two other presidential advisers and the two top officials in the ruling Gabonese Democratic Party (PDG) "have been arrested," a military leader said.
They are accused of treason, embezzlement, corruption and falsifying the president's signature, among other allegations, he said.
A worried-looking Bongo, in a video from an unidentified location, appealed to "all friends that we have all over the world... to make noise" on his behalf.
"My son is somewhere, my wife is in another place and I'm at the residence and nothing is happening. I don't know what's going on. I'm calling you to make noise."
On the streets of the capital, as well as the economic hub Port-Gentil, groups of joyous people were seen celebrating. In Libreville, around 100 people shouted "Bongo out!" and applauded police in anti-riot gear, an AFP staff member saw.
Bongo was first elected in 2009 following the death of his father Omar, who had ruled the country for 41 years, reputedly amassing a fortune.
The coup announcement came just moments after the national election authority declared Bongo had won a third term in Saturday's election with 64.27 percent of the vote.
Gabon's main opposition, led by university professor Albert Ondo Ossa, had angrily accused Bongo of "fraud", and demanded that he hand over power "without bloodshed."
The authorities at the weekend imposed an overnight curfew and shut down the internet nationwide. The internet was restored on Wednesday morning after the TV address.
Gabon's 2016 elections were marked by deadly violence after Bongo edged out rival Jean Ping by just 5,500 votes, according to the official tally.
In 2018, Bongo suffered a stroke that sidelined him for 10 months and fuelled accusations that he was medically unfit to hold office.
The central African country of 2.3 million people has been ruled by the Bongos for more than 55 out of its 63 years since independence from France in 1960.
The White House said it was closely watching the situation, while the AU said it "strongly condemns" the claimed takeover as a violation of its charter.
In Nigeria, Africa's biggest economy and most populous country, President Bola Tinubu said he was in contact with other African heads over the "contagious autocracy we have seen spread across our continent."
"Power belongs in the hands of Africa's great people and not in the barrel of a loaded gun," Tinubu said through his spokesman.
Since 2020 there have been military takeovers in Mali, Guinea, Sudan, Burkina Faso and Niger.
In France, were the loss of Bongo would mark a further blow to Paris' reach in Africa, the government said it "condemns the coup" and reiterated its desire "to see the results of the election respected, once they are known."
Russia said it was "deeply concerned" by the situation, while China called for "all sides" in Gabon to guarantee Bongo's safety.