At least three Burundian soldiers were killed and five others injured in an attack outside of the capital Bujumbura at the weekend, police and media sources said on Monday.
According to SOS Medias Burundi, a collective of independent journalists, an army truck was ambushed on Sunday night in the town of Gihanga, 15km from the capital.
"A truck with about a dozen soldiers on board was ambushed by an unidentified armed group while on their way to an army position in Rukoko," a police source confirmed on condition of anonymity.
"Three soldiers were killed on the spot and five others were injured, three of them seriously."
The region lies alongside a swampy area bordering the Democratic Republic of Congo, where Hutu National Forces of Liberation rebels are known to be active.
Burundi been wracked by a political crisis since 2015, when President Pierre Nkurunziza ran for a controversial third term and won a disputed election.