An official in Congo's restive northeast region says an unexplained grenade explosion has killed two people and injured 31 peacekeepers.

Julien Paluku, governor of North Kivu province, said the explosion occurred Tuesday morning as the peacekeepers were exercising on the outskirts of Goma, the provincial capital on the Rwandan border.

He said one of the dead was a peacekeeper and the other was an 8-year-old child. He said officials were investigating whether the grenade belonged to the peacekeepers or whether it had come from some other source.

Various rebel groups are active in Congo's northeast, though most recent violence has occurred in the Beni region north of Goma.

A spokesman for Congo's U.N. mission was not immediately reachable.