Guinea has been rocked by violent protests after provisional election results showed President Alpha Condé, 82, was on course to win a controversial third term.
The government has deployed soldiers to assist the police, and gunfire erupted in the capital, Conakry, on Friday.
Opposition leader Cellou Dalein Diallo has alleged large-scale fraud and declared himself the winner.
Internet and phone services have been cut in the West African nation.
Ethnic clashes during the campaign had raised fears of nationwide violence if the results were disputed.
Africa Live: Updates on this and other stories
- Prison to president: The 82-year-old eyeing six more years
- A quick guide to Guinea
What’s the latest?
According to sources contacted by the BBC, the army has been called in to support the police in maintaining order.
Witnesses told Reuters news agency there had been gunfire in the Sonfonia neighbourhood of Conakry and a local resident said police had used warning shots to break up protests.
Residents in opposition strongholds say that many people are holed up in their homes and that the police are using live ammunition instead of tear gas against protesters.
Communications by telephone are barely going through and the internet has been shut down.
At least 10 people, including two police officers, have been killed since Sunday’s poll, according to the authorities. Other sources put the figure at 20 deaths.
Results released from 37 out of 38 constituencies show Mr Condé gained 2.4 million votes, well ahead of Mr Diallo with 1.2 million votes. Some other opposition groups boycotted the poll.
Candidates need more than 50% of the vote for outright victory, or there will be a second round on 24 November.
Some 5.4 million people were eligible to vote.
Despite widespread criticism, Mr Condé pushed for a change of the constitution making him eligible to seek re-election.
Months of protests have often turned deadly. At least 12 people were killed in the week leading up to the election.
Five things about Guinea:
- Independence leader Sékou Touré told France in 1958: “Guinea prefers poverty in freedom than riches in slavery”
- “Black power” civil rights leader Stokely Carmichael moved from the US to Guinea in 1968, with his then-wife, the singer Miriam Makeba, becoming a life-long proponent of pan-Africanism
- It has the world’s biggest reserves of bauxite – the main source of aluminium
- Its Mount Nimba Strict Nature Reserve, a Unesco World Heritage Site, is known for its viviparous toad and chimpanzees that use stones as tools
- Singer Mory Kanté, famous for the 1980s hit Yéké Yéké, came from a well-known Guinean family of griots, or praise-singers
Who is Alpha Condé?
Mr Condé was a veteran opposition leader who finally won elections in 2010, marking the first genuinely democratic handover in Guinea since independence.
He served jail time for challenging Gen Lansana Conté, who ruled from 1984 to his death in 2008.
He campaigned on his economic record and prospects that Simandou, one of the world’s largest untapped iron-ore deposits, might finally be exploited – creating thousands of jobs.
But critics say that any economic growth has not filtered down to the bulk of the population. Power cuts are common and many young Guineans are unable to find work.
A new constitution was approved in a referendum in March. Mr Condé argues this means he is allowed to seek re-election, even though he had already served the maximum of two terms allowed under the previous constitution.
The opposition disputes this and street protests have led to dozens of deaths over the past year.
Who is his main challenger?
Cellou Dalein Diallo, 68, a former prime minister, is the only formidable opponent. He lost to Mr Condé in both 2010 and 2015, although he says both elections were marred by widespread fraud.
He is a member of the Peul, or Fulani, community. Although they are Guinea’s largest ethnic group, the country has never had a Peul president and many ethnic Peuls say they have faced discrimination, dating back to the days of President Sékou Touré, when thousands fled the country.
Mr Condé is largely backed by members of his Malinké community, as well as the country’s third major ethnic group, the Soussous.
Mr Diallo and other opposition figures in the National Front for the Defence of the Constitution (FNDC) had vowed to boycott an election which they felt could never be fair.
But in early September, Mr Diallo broke with the FNDC, announcing that he would run after all.
The FNDC has called for nationwide protests from Monday.
Guinea elections: Violent protests as Alpha Condé set for victory – BBC News