KINSHASA, Congo (AP) — A boat heading from Tanzania to Congo on Lake Tanganyika capsized Thursday, leaving at least 41 people dead, local authorities said.

The boat was carrying about 100 people as well as cargo, said Norris Mulongoyi, the provincial transport minister for Tanganyika province, adding that 49 people have been rescued and a search is ongoing for the remaining passengers.

“The vessel, traveling from Kigoma, Tanzania, to the city of Kalemie in the Congo’s Tanganyika province, capsized near the village of Mapera,” Mulongoyi told The Associated Press.

Lake Tanganyika is the world’s largest freshwater lake and the second deepest, after Lake Baikal.

The cause for Thursday’s tragedy was not immediately clear, but hundreds have been killed in boat disasters in Congo in recent years. Vessels are often overloaded and lacking life jackets.

Congo’s rivers are a major means of transport for its more than 100 million people, especially in remote areas where infrastructure is poor or nonexistent.