Fiji police say villagers have reported houses being blown away by Cyclone Tomas moves slowly over Fiji's northern island of Vanua Levu.
One of 16 people sheltering in a government building on Taveuni Island, 6.5 kilometres east of Vanua Levu, told Radio New Zealand boats have ended up on the main road.
Winds are gusting up to 270km/h at the centre of the Category 4 storm, the second-most destructive on a five-point scale.
Police say they are regarding the death of a 31-year-old woman swept out at sea on Friday afternoon as the first victim of Cyclone Tomas.
Spokesperson Atunaisa Sokomuri says the woman and her relatives were swept out at Namilamila Bay in Vanua Levu after a warning to stay away from the sea was issued.
Cyclone Tomas has so far lashed northern parts of Fiji with estimated average winds of about 175km/h, which are expected to increase to about 200km/h within 12 hours.
People in the eastern islands are bracing for destructive hurricane force winds with gusts as strong as 230km/h, and the rest of Fiji has been told to expect gusts of up to 110km/h.
Heavy rain and flooding are also expected, with very high seas and damaging swells.
The cyclone, which is moving south at 10km/h, is expected to lie 210 kilometres east-north-east of the capital, Suva, by 9am Tuesday.
Damage reported
The Fiji Disaster Management Office says Cyclone Tomas is one of the most powerful cyclones to hit the Fiji group in recent years.
The disaster centre on Vanua Levu says houses have been damaged, particularly in remote settlements and villages on the outer islands.
There have been reports of roofs being torn off homes, trees being uprooted and low-lying areas affected by seawater.
The centre says the real extent of damage will not be known until the cyclone has passed.
More than 5000 people have taken shelter at evacuation centres on Vanua Levu, with the number of centres boosted to 90.
A curfew was imposed again overnight, from 8pm Monday to 7am Tuesday, for the central, eastern and northern divisions so emergency services could perform more effectively.
Fiji's permanent secretary for information, Lieutenant Colonel Neumi Leweni, says about 100 army and police personnel are on standby in Vanua Levu.
NZ monitoring
New Zealand officials say they are monitoring the cyclone and are ready to help if needed.
The Ministry of Foreign Affairs and Trade (MFAT) says initial indications are that the damage in Fiji's northern, eastern, and central divisions could be significant.
MFAT says there are 446 New Zealanders registered with the Ministry as being in Fiji and about 60 registered as being in Solomon Islands, which was earlier affected by Cyclone Ului.
However, Prime Minister John Key says the number in Fiji is likely to be greater.
Auckland International Airport says two Fiji Airlines flights which were scheduled to leave on Monday have been postponed until Tuesday.
Damage to Wallis and Futuna
Cyclone Tomas earlier hit Wallis and Futuna to the north of Fiji, causing damage to houses and crops.
Wind gusts of up to 200km/h were recorded in the French territory. It is reported that many traditional houses have withstood the cyclone better than newer homes.
French Overseas Territories Minister Marie-Luce Penchard says France is ready to assist the population of Wallis and Futuna, should it be necessary.
