(CNN) -- Rescuers were scheduled to resume their search Friday morning for survivors of a ferry that sank off the Tanzanian island of Zanzibar, killing 60 people and leaving more than 80 people unaccounted for, the Red Cross said.
As night fell Thursday, crews halted their search until the next morning, the Red Cross said.
The vessel with about 290 people aboard -- including 31 children -- capsized near Zanzibar on Wednesday, according to a spokesman for the agency's office in Tanzania.
About 145 people have been found alive, and rescue operations are ongoing, said Raymond Kanyambo, a spokesman for the agency.
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Authorities intensified efforts Thursday by using army helicopters, government troops and boats.
Strong winds and rough waves, which officials blame for the capsizing, complicated ongoing rescue efforts, he said.
Ferries in the region often carry passengers not included in the manifest, making it hard to pinpoint the exact number of people aboard.
The ferry was traveling between the Tanzanian commercial capital of Dar es Salaam and Zanzibar, the Indian Ocean archipelago popular with tourists for its pristine sandy beaches.
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Zanzibar is a semi-autonomous part of Tanzania.
The capsizing Wednesday is the latest such disaster in the popular tourist destination of Zanzibar in less than a year.
More than 200 people perished when a crowded ferry traveling between two islands of Zanzibar sank in September. In that incident, the ferry had a capacity of about 600 passengers, but was carrying more than 1,000 people, officials said at the time.
Tanzanian authorities charged five men with negligence in the September capsizing, including the owner of the ferry and the captain.