Tropical Cyclone Tomas is moving slowly over the Fiji islands, bringing winds of up to 270 kilometres an hour and heavy rain.
It has torn through the islands of Vanua Levu and northern Lau and is pounding villages with high waves, damaging winds and torrential rain.
The Category 4 storm, the most powerful to hit the area in seven years, has made its way south to the eastern island groups of low-lying Lau and Lomai Viti, where the Fiji Broadcasting Corporation is reporting there is a threat of high waves.
A change in direction of the cyclone means that the capital Suva and Nadi have so far escaped the worst of the damage. But a Fiji police spokeswoman says they are still bracing for the rest of the cyclone to hit, which is due to reach Suva within the next 18 to 24 hours.
Strong winds are battering the area and a sea wall has been destroyed, she says.
Fiji Tropical Cyclone Centre senior forecaster Matt Boterhoven says the epicentre of the storm is about 240km east from Suva.
It is moving through northern and eastern islands, which are not highly populated, but prone to flooding.
The cyclone is expected to leave the islands and head to the open ocean in about 24 hours, Boterhoven says.
It could be up to 36 hours before sea swells calm down.
"That's going to be a real problem for the next day and a half."
Aid might not be able to reach some damaged islands until Thursday, he says.
Taveuni, Rabi, Kioa islands are likely to have been affected, and there are concerns around flooding in Labasa, and Viti Levu especially Coral Coast area. It is also likely that there will be loss of crops and damage to infrastructure in affected areas.
Tomas has already hit Vanua Levu, Fiji's second-largest island, and about 5,000 people have been evacuated to emergency centres from their homes.
There is still no communication from Vanua Levu due to loss of electricity, mobile and satellite communications.
The cyclone has also caused communication and power outages on many of the other islands.
The director of Fiji's Disaster Management Centre, Pajiliai Dobui says communication has been lost with Taveuni and the Lau group, where the storm is currently.
"(It's - Tomas) cutting off communications, pounding villages with tidal waves and relentless damaging winds and as we speak now the Lomai Viti group and the Lau group are bearing the full brunt," says Dev Narayan of the Fiji Broadcasting Corporation.
The commication loss hampering the centre's ability to assess the true extent of damage and Doubi says officials will not know what damage had been caused there until Wednesday.
The Pacific Island nation had prepared well for the onslaught.
"People were advised from the first day to be prepared for this, and that they would be facing the full brunt of the depression," says Narayan.
More than 10,000 people have been evacuated from villages to 90 shelters in the northern Fijian islands and a curfew was imposed on Vanua Levu after fears of possible looting.
There have been no reported casualties overnight. The only casualty so far is 31-year old Tamarisi Tabua who was swept to her death at Labasa, on the northern island of Viti Levu, saving her sisters and two children from a huge wave on Saturday.
At least 480 Kiwis are known to be in Fiji and the Ministry of Foreign affairs say they are believed to be safe and well.
The New Zealand government has urged New Zealanders in Fiji to monitor local radio and follow any advice issued by the local authorities as well as register with the High Commission in Suva.
Anyone travelling to the affected areas should closely watch the government's safe travel website, Prime Minister John Key says.
Meanwhile, the other major Pacific cyclone, Ului, is looking less likely now to threaten the Queensland coast.
The Category 5 earlier brushed the Solomon Islands but the damage has not been as bad as feared, though it is whipping up gale force winds.
Rough seas have also forced the temporary removal of shark nets
along the Gold Coast and Sunshine Coast.
Do you have images or video of the storm? Email them to us at email@example.com
Auckland based Indian radio station, Apna Radio, is holding a 40-hour radio-thon to raise money for those affected by Cyclone Tomas. Find out how to donate here.