Communications to the Ha'apai island group in Tonga's central region have been cut after Cyclone Ian slammed into the region.
Leveni Aho from the National Emergency Management Office says before communications went down, his office received some reports of structural damage from the region.
"A number of buildings roofs have been taken off and we still have no reports of any deaths or missing or major injuries as yet," he said.
"There were no reports like that prior to the communications blackout."
Earlier on Saturday, the Category Four cyclone hit the Vava'u island group in Tonga's north, bringing winds estimated at 200 kilometres per hour.
Mr Aho says while some roofs were blown off churches in Vava'u, Ian appears to have caused less damage than expected.
"Our team is still in Vava'u going through from village to village getting assessment on the extent but by the sounds of things Vava'u has been lucky so to speak, they did not sustain too much damage as expected," he said.
He says power has been restored to Vava'u's main town Neiafu and should be restored to the remainder of Vava'u within 24 hours.
There are no reports of injuries or deaths from across the country.
Deputy prime minister Samiu Kuita Vaipulu told reporters some houses were blown down at Foa.
He says although Australia and New Zealand have aid services on standby, at this stage there is no need for any outside assistance.
However, a state of emergency has been declared for the northern islands, with reports of damage to homes on Hunga.
Tonga's capital, Nuku'alofa, is not directly in Ian's path but will experience damaging gale-force winds, heavy rains and sea flooding of low-lying areas.
The cyclone had been rated a category five, but was downgraded to a category four early on Saturday morning.
However the storm remains incredibly fierce.
Fiji-based climate analyst Neville Koop says the cyclone will pass to the east of the capital Nuku'alofa but they could also experience damaging winds later tonight.
Aussies rely on texts from home
A group of Australians sheltering in a guesthouse on Tonga's Lafuka island say they are relying on text messages from home to keep them informed about the cyclone's strength and path.
Hobart student Rob Hortle, 24, says locals have begun boarding up windows and evacuating to a local church for safety.
"We've got no radio or internet or anything so we don't know much more then what we can see out of the window," he said.
"We feel pretty safe where we are but the lack of information is a bit concerning.
"But hopefully we can keep getting reports from home via text and that sort of thing."
Tonga 'lucky' to have escaped Ian's worst
Tonga's National Emergency Management Office says the country is fortunate to have escaped the worst effects of Cyclone Ian.
Mr Aho says although the danger period is not over, many Tongans are counting their blessings.
"Yes, it's very strange how the eye of the cyclone was very narrow and yet so powerful," he said.
"I think we are extremely lucky with very little damage reported."
Tonga's Tropical Cyclone Warning Centre is forecasting extremely high seas and flooding of low-lying coastal areas.
On its , Ian is expected to continue its south-east course.
"Possibly the speed will increase and it is expected to move away from the Tongan group from 11:00pm-midnight," Sanjay Prakash, from the Fiji Meteorological Service, said.
Hotel manager, Kjell Stave, is bunkered down with his wife, child and six guests on Vava'u, which was hardest hit by the storm.
"I'm sitting in my house all boarded up. I have some small windows I can peek out and it's... certainly one of the highest wind speeds I've ever seen," he said.
"It was a category five when it came towards our island, but it seems like just a few hours ago, it veered a little bit west.
"So we could have been lucky here, not sure yet, but we could have been.
"There is a significant difference between being 30km from the eye and 50km - that's half the windspeed. So we could have been lucky."
Mr Stave told Radio Australia a "massive clean-up" will be needed once the storm passes Ha'apai.
"They don't have much protection. They may get some serious damage down there."
He says they have been able to feel the force of the storm, and his power has gone out.
"I can see some boats fetching and rolling about here," Mr Stave said.
"It's starting to build up some chop in the bay; we are fine, but we will have to see now."
Military ready to provide support
The Pacific office of the UN Office for the Coordination of Humanitarian Affairs says Tonga's National Emergency Operations Committee met on Thursday to discuss preparedness activities.
The Tongan Red Cross Society has emergency response teams on standby and can access pre-positioned non-food items across five islands.
The New Zealand government has additional personnel at the High Commission to support assessment and response planning.
Military assets are also available for reconnaissance and logistical support if required.
© ABC 2014
18:04 EDT The weather bureau has urged residents in Queensland's Gulf to remain on cyclone alert as ex-Tropical Cyclone Gillian moves overland.