People stockpiled food, police manned major crossroads and soldiers were deployed at petrol stations and banks on Tuesday as Gabon braced for results from a election that will decide the fate of Ali Bongo and his family's 50-year grip on power.
Bongo's main challenger for the presidency, Jean Ping, a former foreign minister, African Union Commission chairman and lifelong political insider in Gabon, has already declared victory.
He urged Bongo, first elected in 2009 after the death of his father Omar, who ran Gabon for 42 years, to acknowledge defeat.
Bongo's supporters, however, say he is on track to win.
With both sides trading accusations of fraud after a bitter campaign, there was widespread concern that the results, set to be announced from 7 p.m. (1800 GMT), would trigger unrest.
"There will be trouble and Ali will tackle the problem with his men ... We're afraid of the spillover," said Jadi Mabende, 57, a civil servant at a shop in the capital Libreville.
Several African governments have shut down mobile telephone networks, Internet and social media during contentious elections over the past year to prevent people organising protests, although there were no signs yet of that happening in Gabon.
However, the army said in a statement that customs officials had seized some illegally imported satellite telephones.
The embassy of France, Gabon's former colonial ruler, advised its citizens on Tuesday to stay indoors after 2 p.m. and to stick to safety precautions.
France's ruling Socialist Party took the unusual step of declaring that early results showed Ping defeating Bongo, just a day after Saturday's poll.
"We're in a situation of suspense. We're ... worried about the demonstrations that are going to happen," said Libreville resident Franck Boubzanga, 33.
Gabon's first-past-the-post system means the winner only needs more votes than any other candidate. In 2009, Bongo won with 41.73 percent.
The European Union's observer mission on Monday criticised a "lack of transparency" among the institutions running the polls and said Bongo had benefited from preferential access to money and the media.
"We've noted that the mission overstepped its mandate. This mission was looking into things that had nothing to do with this election," Bongo's spokesman Alain-Claude Nze said, reacting to the EU's statement on French radio RFI on Tuesday.
Bongo, 57, also benefited from being the incumbent in a country with a patronage system lubricated by oil largesse.
But oil output and prices have fallen, forcing budget cuts despite Gabon having one of the biggest revenue streams of all Africa's oil producers.
Gabon's economic troubles have provided fodder for opposition claims that its 1.8 million inhabitants have struggled under his leadership, and Bongo's ruling party has suffered a series of high-profile defections.
(Writing by Joe Bavier; Editing by Tim Cocks and Louise Ireland)