At least six people have died and thousands are without power or water after Cyclone Gene lashed Fiji.
Winds gusted at 140km/h (88mph), tearing off roofs, causing flooding and bringing down trees and power lines, disaster officials said.
Hundreds of people took refuge in schools and government shelters after fleeing damaged houses.
Forecasters warned of further serious flooding, as the tail-end of the storm dumped large amounts of rain on Fiji.
The cyclone is moving slowly westward towards Vanuatu, forcing the authorities there to issue a cyclone alert.
'Caught off balance'
Much of the damage was confined to Fiji's main island of Viti Levu.
Two workers were killed when they were hit by falling power cables near the city of Lautoka, the Fiji Electricity Authority said.
Officials said at least four others had died on Vita Levu.
Meanwhile, the electricity authority said power had been cut "all over Fiji".
"All schools and civil service offices are closed until power and water are restored," authority spokesman Aisea Quminakelo told the Associated Press news agency.
Many Fijians living on the west side of Viti Levu, the country's main tourist centre, moved to higher ground after the forecasters warned of heavy seas and coastal swells, AP reports.
Pajiliai Dobui, from the Disaster Management Office in the capital Suva, told Radio Australia the cyclone had not behaved like others.
"We were not really ready for it since the hurricane just developed all of a sudden, and then we were caught off balance when it struck," he said.
"This one really followed a pattern that is quite different from the pattern that we normally follow. It is quite unique in a way."