At least 190 people died yesterday and another 40 people are in a “serious condition” after an overloaded ferry sank off with almost 600 onboard between Zanzibar and Pemba island, Tanzania.

Tanzanian government called for an immediate investigation to uncover the reasons for the disaster.

Survivors of the ferry disaster in Zanzibar

“The ship’s manifest shows that the vessel travelling from Unguja to Pemba islands had more than 500 passengers on board,” Zanzibar Police Commissioner Mussa Alli Mussa said.

“Some 260 passengers have so far been rescued … we have recovered several bodies but I can’t give you the exact death toll at the moment because the situation is very volatile,” he said.

190 people drown in the ferry tragedy in Tanzania

Passengers described the terrifying moment when they realized something had gone wrong, with people began to scream as the boat tilted to one side and water rushed in.

“I realized something strange on the movement of the ship. It was like zigzag or dizziness,” said 15-year-old Yahya Hussein, who survived by clinging to a plank of wood with three others.

“After I noticed that I jumped to the rear side of ship and few minutes later the ship went lopsided.”

Hussein said there had been many children aboard the ship.

“After the ship began to list, water rushed through the main cabin and stopped the engines,” said Mwita Massoud, another survivor.

Those passengers lucky enough to find something to cling to floated in the dark waters for at least three hours until the strong currents began to wash them up on the white sandy shores of Zanzibar.

Throughout the day, police waded through the clear waters to shore, carrying bodies on stretchers, wrapped in brightly colored cloth and blankets.

Tourists on the popular island of Zanzibar helped survivors and local charities provided blankets and tea.

Tourists on the popular island of Zanzibar helped survivors and local charities provided blankets and tea

Pemba island is about 25 miles from Zanzibar. Passengers who regularly take ferries between the two islands said the vessels are in a poor state of repair and are often overcrowded and loaded with cargo.

“They normally pack us in like sardines in a can. And for that I really fear this could be a very big disaster,” said resident Mwnakhamis Juma.

The government in Zanzibar said last month it planned to invest in bigger, more reliable vessels to ferry passengers between the two islands.

“We are fearing the greatest calamity in the history of Zanzibar. This is a disaster,” said a government official, who declined to be named.

In 2006, another ship capsized in Zanzibar, killing hundreds of people. But the government still did not invest in better ferries or boats capable of mounting a rescue.