Four civilians and a soldier were killed and three others were wounded in the shooting yesterday.
"A group of four armed criminals wearing long coats entered ... They started shooting at customers," police spokesman Moise Nkurunziza said.
Hundreds have been killed and a quarter of a million people have fled Burundi since President Pierre Nkurunziza's controversial decision last April to run for a third term, a vote he won amid opposition boycotts in July.