Soldiers went on Gabon's state radio early on Monday, saying that a "national restoration council" had been formed in the country, with President Ali Bongo convalescing in Morocco after a stroke.
Shots were heard in the area near the state television offices in the center of Libreville.
Bongo suffered a stroke in October and has since been out of the country receiving treatment.
The soldiers said that the president's recent televised New Year's Eve address "reinforced doubts" about Bongo's "ability to carry out the responsibilities of his office," according to Lieutenant Kelly Ondo Obiang. Obiang leads the self-declared Patriotic Movement of the Defense and Security Forces of Gabon.
Government spokesman Guy-Bertrand Mapangou told DW that the situation was under control, with four co-conspirators arrested. Obiang is currently on the run, "but we will soon have him," Mapangou said. Hours later, the presidency said the failed coup leader was arrested and two of his soldiers killed.
African Union chief Moussa Faki Mahamat "strongly condemned" the events that took place in the Gabonese capital in a message on Twitter. "I reaffirm the AU's total rejection of all unconstitutional change of power," he wrote.
Bongo family: Half-century of rule
The 59-year-old president was hospitalized in October in Saudi Arabia. Since November, he has been continuing his treatment in Morocco.
Bongo had acknowledged health problems in his New Year speech but said that he was recovering.
Gabon is one of Africa's top oil producers, France's closest ally in the region and has been ruled for more than 50 years by the Bongo family. Ali Bongo succeeded his father, Omar, who died in 2009.
Despite its natural resource wealth, about one third of Gabon's population still lives below the poverty line. The African nation has been struggling economically since 2015, facing rising unemployment, repeated labor strikes, companies operating on slowdown, and austerity measures being imposed.
msh/jcg (AFP, Reuters)