Nearly 200 people have died after a ferry travelling from Zanzibar to Pemba island off the East African country of Tanzania capsized overnight, police said.
Zanzibar police spokesman Mohamed Mhina told the Reuters news agency that 192 bodies had been recovered and 606 passengers rescued from the Indian Ocean so far.
"There is a possibility that more bodies still remain at sea. Rescue workers are still searching for survivors and
retrieving bodies," he said.
"The ferry flipped and capsized. There could be more bodies trapped inside the hull of the ship with the cargo," rescue worker Ali Ramadhan told Reuters at the port.
"We suspect the ship was overcrowded with more than 800 passengers onboard. It is normal for these ferries to overload passengers and cargo."
Zanzibar Police Commissioner Mussa Alli Mussa said early on Saturday that more than 500 people were on the ship's passenger list.
"The ship's manifest shows that the vessel travelling from Unguja [Zanzibar] to Pemba islands had more than 500 passengers on board."
Mussa said rescue workers with the aid of some fishing boats in the area were helping to rescue more passengers and recover bodies.
Zanzibar and Pemba are the two main islands of the Zanzibar archipelago, a popular destination for tourists visiting their pristine Indian Ocean beaches.
"We are fearing the greatest calamity in the history of Zanzibar. This is a disaster," a government official in Zanzibar, who declined to be named, told Reuters.
Abdullah Saied, one of those rescued from the ferry, said the MV Spice Islander was heavily overloaded and sank in an area with heavy currents in deep sea between mainland Tanzania and Pemba Island at about 1am local time.
Thousands of residents mobbed the docks of Stone Town on Zanzibar, an island near Pemba, waiting for news, The Associated Press reported.
One man was screaming that he had lost 25 members of his family, including his sisters, his wife and grandsons. He was too upset to give his name.
Many of those present expressed anger that the ship had been allowed to leave port so overloaded and called on government officials to resign.
"The cause of the accident cannot be confirmed at the moment," Mussa, Zanzibar's police commissioner, said.