A suicide bomber struck a restaurant in the city of Beni in east Congo on Saturday, killing at least five people and himself, Beni's mayor said.
The attack marks the latest violence in a region where Congolese and Ugandan forces have launched a campaign against suspected Islamists.
"There were five people killed in the explosion, plus the bomber, making six," mayor Narcisse Muteba Kashale said.
Congo's government spokesman Patrick Muyaya said on Twitter that the explosion had indeed been caused by a suicide bomber, and that security forces were investigating the incident.
There were no immediate claims of responsibility.
Congo and neighbouring Uganda launched a military campaign in the area at the end of November against the Allied Democratic Forces (ADF), a group aligned with Islamic State. Officials have previously blamed the group for bombings in the region.
Beni's mayor Narcisse Muteba Kashale earlier told local radio that a bomb had exploded in the city centre. "For safety, I'm asking the population to stay home," the mayor said.
A journalist nearby said he heard an explosion around 7 p.m., just after the afternoon Catholic mass, near the city's main road, followed by gunshots.
Police spokesman Nasson Murara said that officers fired live rounds to disperse an angry crowd that attempted to bar investigators from accessing the scene of the explosion. No one was injured, he said.
Images shared on social media showed dozens of green chairs scattered across a road, some melted or smouldering. At least four bodies, including that of a small girl, could be seen among the wreckage.
The joint Congolese and Ugandan campaign, launched on Nov. 30, had planned to target four ADF camps, including two in the Beni area, a Ugandan general had said earlier this month.
Beni was rocked by two explosions in June at a Catholic church and at a busy intersection. No one was killed in either blast apart from the suspected bomber, who was killed by the second explosion.