Authorities say at least 129 people are dead in Congo after a boat sank on a lake in a remote corner of the enormous country.

Laurent Kahozi Sumba, the transport minister for Katanga province, said Sunday that the true toll of the disaster is not known — 129 bodies have been recovered and there are 232 known survivors.

Many boats in Congo carry far more people and cargo than are listed.

The disaster is believed to have happened early Friday in southeastern Congo. The MV Mutambala was a private boat that connected towns in Katanga and South Kivu provinces.

Kahozi said an investigation is underway to determine the cause of the sinking.