Cyclone Gita strengthens again and heads for Vanuatu and New Caledonia after battering parts of southern Fiji with winds of nearly 200 kilometres per hour.
Cyclone Gita has been upgraded to a category five storm after battering parts of southern Fiji.
Residents on low-lying islands said several homes were flattened and crops were wiped out when the cyclone pounded their villages.
"We were afraid, we were terrified," Noah Sukanasau told the ABC's Pacific Beat program.
Australia and New Zealand have flown emergency aid supplies to Tonga where the clean-up from Cyclone Gita has begun, and as the category-four storm intensifies and heads west towards nearby Fiji.
The Australian Government said it was sending $350,000 worth of emergency supplies to Tonga immediately.
The Minister for International Development and the Pacific, Concetta Fierravanti-Wells, told ABC Radio Australia's Pacific Beat Program the Royal Australian Air Force was flying the aid to Tonga on Tuesday night.
Winds top 230 kilometres per hour
No reports of deaths
Hundreds of military personnel begin clean-up
Cyclone heading for Fiji
The Parliament building in the Pacific country of Tonga has been flattened after a powerful cyclone battered the main island, causing extensive damage.
With destructive winds of 230 kilometres per hour, category four Cyclone Gita ripped roofs from houses, brought down trees and caused widespread flooding.
Tens of thousands of people on Tonga's main island are preparing for the worst as Cyclone Gita bears down with category four force.
Bringing destructive winds and storm surges, Gita is expected to start affecting the island Tongatapu, where more than 70,000 people live, on Monday afternoon.
Tonga's National Emergency Management Office said it was still calm in the capital but that was expected to change soon.
"From our end we are alerting people to be prepared," director of Tonga's National Emergency Management Office Leveni Aho said.
By Pacific affairs reporter Liam Fox
A state of emergency has been declared in Tonga as the country prepares for the arrival of what could be the strongest cyclone to ever hit the country.
Tropical Cyclone Gita is currently a category four storm but it is expected to intensify into a category-five storm as it heads for Tonga's main island Tongatapu and the capital Nuku'alofa, generating winds of more than 200 kilometres an hour.