KINSHASA, Democratic Republic of Congo — About 150 people were missing after a boat sank in an eastern lake in the Democratic Republic of Congo, President Felix Tshisekedi said on Twitter on Tuesday, a day after the vessel went down.

“I am very saddened by the sinking of a boat on April 15 at Lake Kivu. The provisional toll is 150 missing,” Mr. Tshisekedi said on the president’s official Twitter account. “I express my sincere compassion to the families who have suffered. I am closely watching the situation to identify and sanction the perpetrators.”

The boat set off Monday from the village of Kituku, near the city of Goma on Lake Kivu’s northern shore, and sank in South Kivu Province near the territory of Kalehe.

Vital Muhini, the national deputy from South Kivu Province, said the cause of the sinking was unknown. “For the moment, we want to have the exact number and the names of the victims who have embarked on this boat,” Mr. Muhini said.