Rescuers were searching for 18 people missing off Cape Verde Friday after a ferry capsized on its way from the capital Praia to the island of Fogo in the south.

Four people -- three of them crew members -- were rescued after the ferry Vicente sank on Thursday three nautical miles (six kilometers) from Fogo, fire brigade chief Arlindo Lima told local radio.

Bad weather in the archipelago off the west coast of Africa has been hampering the rescue operation to find survivors.

"We have been working with two boats that are not ideal for conducting rescue operations. We are have asked Angolan authorities for the use of their aircraft to help with the efforts," Lima said.