Gunmen wearing police and army uniforms killed three people and injured three others at a bar in a heavily guarded neighbourhood of Burundi's biggest city Bujumbura late on Friday, police and residents said.
The attack took place in the Rohero district, where violence is rare and officials often have the protection of their own security personnel.
"Unidentified evildoers armed with AK 47s attacked peaceful people having a drink at a bar, leaving three deaths and three injured people," Moïse Nkurunziza, deputy police spokesman, said, adding the attackers also detonated a grenade.
A soldier assigned to work in Rohero as a security guard for a senior official near the scene of the attack said police carried out a search operation early on Saturday but made no arrests.
Burundi moved its capital from Bujumbura, a port on Lake Tanganyika, to the much smaller central city of Gitega last year.
In September, the United Nations said that Burundi was at risk of a new wave of violence as it approaches an election next year with an unresolved political crisis and President Pierre Nkurunziza increasingly portrayed as a "divine” ruler. The government said that report did not reflect reality.
Hundreds of Burundians have been killed in clashes with security forces since 2015, when Nkurunziza ran for a third, disputed term in office. Over the same period, more than 400,000 people have fled abroad, predominantly to Tanzania, Rwanda and Democratic Republic of Congo.
On Oct. 22, police said security forces killed at least 14 armed men who had planned to launch an attack in the northwestern province of Bubanza after entering from neighbouring Democratic Republic of Congo.