At least 26 people were injured in a grenade blast near the city centre here, Burundian police said.
Nine of the injured were in a serious condition, Xinhua quoted police as saying.
According to the police, two people riding a motorcycle blasted the grenade on Thursday.
The police said two Kalashnikov, five chargers filled with ammunitions and two bombs were seized on Thursday in a search operation at Mutakura in the north of the capital.
Since April 2015, with the outbreak of protest against the third-term bid of Burundian President Pierre Nkurunziza and his controversial re-election in July 2015, violence has left over 400 dead in the east African nation, according to civil society groups.
