The National Disaster Management Office in Fiji says up to four people are feared dead after Cyclone Mick brought strong winds and heavy rain.
Aid officials say the first cyclone of the season has caused widespread damage across Fiji's main island.
Cyclone Mick swept across Viti Levu overnight, after hitting the popular tourist destinations of the Yasawa and Mamanuca islands yesterday.
Tim Sutton, the deputy representative for Unicef in the Pacific, says it was a very vicious storm.
"A lot of people have been directly affected, there's a lot of damage, even just driving around Suva this morning, lots of trees down, powerlines down everywhere, all the roads in and around Viti Levu are all still closed with flooding, landslides etc."
Tim Sutton says aid teams will be heading out today to assess the need for emergency supplies, food and medicine.
Meanwhile, the Red Cross in Fiji says there is some recorded destruction of households and a tourist resort in the Yasawa Island group says it has been forced to close after it received extensive damage.
Verity Wilson, a staff member at the Octopus Resort, says about 60 guests were forced to take refuge in the resort's cyclone shelter.
She says while there are no reports of any injuries, a couple had a lucky escape from their yacht after it crashed onto rocks.
Ms Wilson says palm trees have been completely stripped of their fronds and tin roofs lifted off many of the resort's buildings.
The resort will be closed for at least five days while staff clean up.