Police used teargas and batons to clear protesters in Libreville
A night-time curfew has been declared in Gabon's Port Gentil after violence by opposition activists and attacks on French interests in the city.
Earlier, opposition groups clashed with security forces in the capital, Libreville, after presidential election results declared Ali Bongo the winner.
France, Gabon's former ruler, has told its 10,000 citizens to stay inside.
Critics say the poll, held on the death of Ali's father, Omar, who ruled the oil-rich state for 41 years, was fixed.
In other violence in Port Gentil, Gabon's second city, opposition supporters stormed a jail, freeing its inmates.
ALI BEN BONGO
Born in 1959 in Brazzaville, his mother is Gabonese singer and musician Patience Dabany
Studied at Sorbonne in Paris before entering politics in 1981
Became foreign affairs minister in 1989 - forced to quit in 1991 because he was too young
Organised pop-star Michael Jackson's visit to Gabon in 1992
Served as defence minister 1999-2009
Source: Ali Ben Bongo's website
They later rampaged through the streets and set fire to the French consulate - as many accuse the former colonial power of propping up the late Omar Bongo's government.
Crowds also attacked installations belonging to the French oil company, Total.
France has about 1,000 troops stationed in Gabon and its International Development Minister Alain Joyandet said "measures were in place" to protect French citizens.
Earlier, police used teargas and batons to disperse protests in Libreville.
Former interior minister Andre Mba Obame, who came second in Gabon's presidential election, told AFP he "does not recognise the results" and that he is in fact the winner.
"This is an electoral coup d'etat. I do not recognise the election results. It is me who won," Mr Mba Obame said by telephone from a secret location.
Opposition leaders have denounced the poll results as a fraud and accuse Mr Bongo and his supporters of carrying out a coup d'etat.
Another of the beaten candidates, Pierre Mamboundou, led protests overnight in Libreville.
A senior member of his party, the Gabonese People's Union, says Mr Mamboundou was seriously injured in the head and shoulder, but was now safe.
Amid the unrest, Ali Ben Bongo pledged to be a uniting force for the oil-rich nation.
"As far as I am concerned, I am and I will always be the president of all the people of Gabon," he said after his victory was announced.
"I am and I will always be at the service of all, without exclusion."
Mr Bongo was widely tipped to succeed his father, who died in June.
One of the world's richest men, the late president owned a string of properties in France and was an unflinching ally of Paris.
A month before his death, French courts began to investigate Mr Bongo for corruption - allegations he denied.
Gabon is sub-Saharan Africa's fourth biggest oil producer and Africa's second biggest wood exporter, although most of its 1.4 million people live in poverty.
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