At least nine people, including seven children, were killed on Friday in a strike at a displacement camp in the eastern Congolese city of Goma, a local official and a military spokesman said.
It was not immediately clear what kind of explosive device was used or who was responsible for the attack.
A two-year offensive by the Rwanda-backed rebel group M23 has moved closer to Goma in recent months, prompting thousands to seek refuge in the city from surrounding areas.
The head of the Lac Vert district where the incident occurred, Dedesi Mitima, told Reuters he had seen the bodies of seven children and two men at the camp.