Explosions and gunfire could be heard Monday in Burundi's capital, Bujumbura, on the eve of a divisive presidential election.
The attacks come against the backdrop of simmering tensions over incumbent President Pierre Nkurunziza's quest for a third consecutive five-year term.
Burundi's opposition has called for a boycott of Tuesday's election, which is going ahead despite months of violent anti-government protests and appeals from the international community for the incumbent to step aside.
The last remaining opposition candidates withdrew from the presidential race, saying the country's political situation, including widespread intimidation and the threat of violence, does not allow for free, fair and peaceful elections.
This pullout by the opposition is seen by many as a blow to the democratic process in Burundi. Its electoral commission notes that the names of the candidates will remain on the ballot papers.
With Nkurunziza as the only candidate, national electoral commission spokesman Prosper Ntahorwamiye said it is uncertain when the results will be announced.
Critics have insisted President Nkurunziza must step aside after serving the two constitutionally allowed terms. But Burundi's constitutional court has ruled he is eligible for a third term because he was chosen by lawmakers, and not popularly elected, for his first term.