More than 130 people died and more than 100 others were missing on Friday, after a ferry travelling between Bugolora and Ukara Island in Lake Victoria near Mwanza sank on Thursday afternoon.
The ill-fated ferry, MV Nyerere, sank at around 2pm, two hours after leaving Bugolora.
Officials blamed the accident on overloading, with Ukerewe District Commissioner Cornel Magembe saying there could have been as many as 400 passengers on board the ferry, whose capacity is 100 passengers and 25 tonnes of cargo.
“There were about 400 passengers on board. Some jumped out and were rescued by local canoe operators,” said Mr Magembe.
Survivors said there had been a truck loaded with maize and cement on board.
It was hard for officials to establish the exact number of passengers aboard the vessel, as the official who was issuing tickets is also missing, and the machine he was using could not be traced by press time.
Inspector-General of Police Simon Sirro, who visited the scene on Friday, said more than 130 people had been confirmed dead.
The death toll was expected to rise as recovery operations continued. Rescuers suspended operations after dark on Thursday, by which time some 44 bodies had been recovered. The rest were recovered on Friday by divers from the Tanzania People's Defence Forces assisted by Red Cross and the police.
The Tanzania Electrical, Mechanical and Electronics Services Agency (Temesa), which runs the ferry services, said the cause of the accident was not immediately clear, but it did not rule out overloading.
Temesa spokesperson Theresia Mwami said the vessel had recently been refurbished, getting two new engines.
Official records show that MV Nyerere was purchased in 2004 for Tsh191 million ($86,800). After a series of mechanical breakdowns and complaints from the public, the two new engines were installed.
President John Magufuli sent a message of condolences to the families of the victims and ordered the arrest of those responsible for the sinking.
Prime Minister Kassim Majaliwa on Friday called off his tour in Chemba district in Dodoma Region to fly to Mwanza to assess the situation.
Kenya’s President Uhuru Kenyatta and opposition leader Raila Odinga sent condolence messages to the Tanzanians.
"On behalf of the people of Kenya, I express our most sincere condolences to my brother President John Magufuli and our dear neighbour. No words can adequately express our grief following this tragic accident. My heart goes out to those who have lost their lives and their families," President Kenyatta said in a statement.
“We, as your neighbour, are deeply heartbroken by what happened. Allow me to express our solidarity and support for our brothers and sisters in Tanzania... and to assure them that we will lend every needed support."
Mr Odinga said on Twitter: "I mourn with the people of Tanzania at this very difficult moment. May God grant peace and strength to the families, the care givers and the Tanzanian nation."
The tragedy brought into focus the issue of safety in Lake Victoria, which claims thousands of lives annually.
Navigating the lake has become a matter of trial and error, maritime experts say, with ancient navigation routes dating back to the 19th century, missing course lights and clogged piers. The lack of equipped weather stations also makes it difficult to predict weather patterns in order to take precautions.
The sinking of MV Nyerere could likely be the second most disastrous marine accident in the lake, after the May 1996 MV Bukoba tragedy that claimed more than 800 lives after it sank just 30 minutes before reaching Mwanza port. Only 53 people survived.
A team, headed by High Court Judge Robert Kisanga investigating the cause of the accident later blamed the tragedy on overloading, and a faulty engine. It took divers, some of them from South Africa and Kenya, to recover the bodies.
The captain of the ship, Jumanne Rume Mwiru, and eight senior officials of the Tanzania Railways Corporation’s Marine Department were charged in with the murder of 615 people.
Lake Victoria Basin Commission
Thursday’s tragedy has also shone the spotlight on the Lake Victoria Basin Commission, which earlier this year announced it had secured $35.8 million from donors to improve safety on the lake, under a project dubbed Multinational Lake Victoria Maritime Communications and Transport. The project is to be implemented by Kenya, Uganda and Tanzania over four years.
A 2012 report by the LVBC showed that accidents in the lake were mostly caused by unstable boats, bad weather, overloading, lack of safety equipment and poor seamanship. The stubborn weed, the water hyacinth, which has choked important waterways and landings, is the latest cause of accidents.
Amos Ndoto, an LVBC maritime safety officer, said the project is important since the lake had become dangerous, claiming thousands of lives each year. He said the regional maritime rescue communication centres in Mwanza, Kisumu and Entebbe would be facilitated to respond to distress calls and locate accident victims and survivors.
The centres would get rescue boats fully furnished with medical facilities to give first aid. There would also be emergency search and rescue stations around the lake, equipped with fast rescue boats and trained crews.
The commission this year distributed navigational aids to the ports of Kisumu in Kenya, Port Bell in Uganda and Mwanza. A total of 86 navigation aids were installed, with Kenya receiving 18 while Tanzania and Uganda which own a larger percentage of lake surface receiving 46 and 22 respectively.
LVBC maritime safety officer Gerson Fumbuka said the navigation aids would guide captains on the right track, just like roads are marked for cars.
“The significance of navigation aids is that they help the ship captains to determine where they are and to enable them to cross each other without colliding, even in the rain,” said Mr Fumbuka.