A group of armed men attacked a hillside area in the town ofKigamba and looted several homes, Jean-Berchmans Niragira said.
Police and soldiers tracked them down and opened fire.
“There was a shooting in which 18 bandits were killed and three guns recovered,” Niragira said, adding that patrols were under way to find other group members.
Kigamba is located about 240 kilometres (150 miles) east of theBurundi capital Bujumbura. The “bandits” were trying to hide out in neighbouring Tanzania, Niragira said.
Local police officials told AFP that the heavily armed group was made up of about 40 people wearing police uniforms.
The group was part of a new rebellion based in Ruvubu National Park in the east of Burundi, the officials said.
An increase in deadly attacks and executions has left many fearing a resumption of broader hostilities in this country devastated by a long civil war that claimed nearly 300,000 lives between 1993 and 2006.
Monday’s attack was one of the worst on record attributed to “armed bandits.”
Such attacks have been intensifying for almost a year across the country.
In September, heavily armed men attacked a bar in a town near Bujumbura and killed at least 36 people.
The trial of 21 suspects will resume December 1.