Protests erupted in Burundi earlier this year against President Pierre Nkurunziza's third-term bid
Heavily armed attackers have launched co-ordinated assaults on at least two army barracks in Burundi.
Eight people, including some attackers, have reportedly been killed in Bujumbura, the capital. Witnesses described hearing gunfire and explosions for several hours, in Musaga in the south and Ngagara in the north.
The incident is the worst violence since an attempted coup in May, sparked by President Pierre Nkurunziza's third-term bid.
UN officials have recently accused both government and opposition figures of stirring up ethnic tension between Hutus and Tutsis, amid fears of a return to genocide.
Bujumbura residents have taken cover at home and are too frightened to go to work or send their children to school, reports the BBC's Prime Ndikumagenga from the city.
The attacks are the first on military targets since the coup attempt, he says.
The neighbourhoods where the attacks occurred are seen as opposition strongholds, correspondents say.
It is not clear who is behind the attacks but a presidential adviser said that government opponents had been trying to create a diversion to free prisoners.
The adviser, Willy Nyamitwe, said the insurgents had failed, describing them as Sindjuma, meaning "I am not a slave".
Mr Nkurunziza won a disputed election in July.
At least 240 people have been killed since April. More than 200,000 people have fled to neighbouring countries, the UN says.
In recent months, there have been daily killings of both opposition activists and Nkurunziza supporters.
