Fifteen people, mostly children, died in a boat sinking on a lake in northeastern Ghana, the country’s maritime authorities announced on Sunday.

A statement from the Ghana Maritime Authority said, “Among the dead are 11 children aged between two and 14 years (five boys and six girls),” following the accident that occurred on Saturday on Lake Volta in the Oti region.

The statement added that “the children and other victims were traveling from Okuma to Bofiem when their boat capsized,” noting that four adults survived and describing the incident as a “serious and unacceptable violation of safety standards.”

The Maritime Authority said a specialized team was deployed to determine the cause of the sinking, noting that “preliminary results indicate the boat was overloaded.”

The authority confirmed it will form a high-level investigation committee with the Ministry of Transport and will launch “an ongoing operation to enforce safety measures along the lake shores,” to ensure compliance with passenger limits and life jacket rules.

Boat disasters are common on Lake Volta, often caused by overloading and collisions with tree trunks.