At least 44 people killed in incident on Lake Victoria as number of passengers on-board the ferry remains unknown.

At least 44 people have died in Tanzania when a passenger ferry capsized in the south of Lake Victoria, local officials said.

The death toll was expected to rise on Friday with rescue operations set to resume at dawn.

Regional governor John Mongella told The Associated Press that 37 people were rescued before operations were suspended for the night, though some of the survivors were in “a very bad condition”.

“According to reports that President John Magufuli has just received from the authorities in Mwanza, the toll now stands at more than 40 dead,” Gerson Msigwa, the president’s spokesman, said on state television.

MV Nyerere sank on Thursday afternoon near Ukara Island, according to Tanzania’s Electrical, Mechanical and Services Agency. In a statement, the ferry operator said it was unknown how many passengers were on-board the vessel.

Accidents like these are not uncommon on Lake Victoria and overloading is often to blame.

Reuters news agency reported it was difficult to establish a number because the person dispensing tickets drowned in the incident.

George Nyamaha, head of Ukerewe district council, said “more than a hundred passengers” were on board when the ferry sank while local media reported numbers as high as 400 to 500.

Al Jazeera’s Catherine Soi, reporting from Nairobi in neighbouring Kenya, said the boat was also carrying cargo when it went down.

“What we also know from witnesses that the ferry appeared to be overloaded. It has a capacity of 100 people,” she said. “The ferry was affected by bad weather as well.”

In 1996, a ferry disaster on Lake Victoria in the same region killed more than 500 people.

In 2012, 145 people died in a ferry disaster in Tanzania’s semi-autonomous archipelago of Zanzibar, in the Indian Ocean, on a vessel that was overcrowded.