BUKAVU, Congo (AP) — A boat capsized on Lake Kivu in eastern Congo on Tuesday, leaving at least 21 people missing, authorities said.

The boat was on its way to the town of Makengere when it sunk after a visit to a market town. Officials said that 23 people survived, and a search was ongoing for the missing.

The cause of the capsizing was under investigation. It wasn't immediately known how many people were onboard or the exact number of missing.

Deadly boat tragedies are common in the central African country, where late-night travels and overcrowded vessels are often blamed.

Because of insecurity in eastern Congo, many people are abandoning the few available roads for wooden vessels crumbling under the weight of passengers and their goods. The roads are often caught up in the deadly clashes between Congolese security forces and rebels that sometimes block major access routes.

“Pending the restoration of peace, we urge the central and provincial governments to become more involved in order to find a lasting solution to this situation,” said Koko Chirimwami Akeem, provincial deputy for South Kivu in a statement.

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.

Hundreds have been killed in boat disasters in recent years.