Violence erupted Wednesday after Interior Minister Pacome Moubelet Boubeya announced the results from Saturday's vote, which showed that incumbent President Ali Bongo defeated opposition candidate Jean Ping by a very slim margin: Bongo had 49.8% of the vote, while Ping, a diplomat and former African Union official, had 48.23.
Turnout was 59%, according to the country's election commission. Nearly 600,000 people were registered to vote.
The final results must be confirmed by the country's constitutional court within a week.
The opposition claimed the results were fraudulent and thousands of people took to the streets of the capital in protest.
The Parliament and other government buildings were set ablaze overnight Wednesday into Thursday, as government forces tried to restore order. Shops and businesses were looted.
Three people died in the violence, Gabon's Interior Ministry announced in a statement Thursday. Hundreds reportedly were injured.
Patrick Obiang, the Red Cross director of operations in Gabon,
told CNN on Thursday that while his teams are still assessing the number of casualties, they have seen at least one body of a protester who was killed in the overnight clashes.
Bongo's re-election would extend his family's half-century rule over the oil-rich nation by another seven years. Bongo took power from his father, Omar Bongo, in 2009, when similar protests erupted.
The US and France have expressed concern about the situation in Libreville and called for restraint by both sides.
The US State Department called on the government to release the results from each polling station, saying "elections must credibly reflect the will of the people."
The government has faced criticism for its response to restore stability and for reportedly interrupting communications.
"I am deeply concerned and saddened about the situation in the Gabonese Republic provoked by the electoral crisis, in particular the arson attacks and disproportionate response of security agencies that has led to unfortunate loss of life and property," UN Secretary General Ban Ki-moon said in a statement.