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.
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.