Queensland Police Commissioner Bob Atkinson has warned people in the north of the state that Cyclone Yasi could still cause damage.
The intensity of the cyclone is subsiding as it moves inland, but Mr Atkinson says there could be more destruction later on Thursday.
He is urging people to stay off the roads until officials can confirm the worst of the cyclone has passed.
Cyclone Yasi came ashore as a category-five storm, but has since been downgraded to category two as it moves inland. It cut a swathe of destruction across northern Queensland during the past 12 hours, tearing roofs off houses, smashing power poles and knocking over trees, but so far there have been no reports of death or serious injury.
Emergency support staff are struggling to enter towns in the north-east because of debris blocking roads.
State Premier Anna Bligh says there have been no reports so far of deaths or serious injuries but emergency crews are yet to reach some people.
Ms Bligh says there is significant damage in many towns such as Mission Beach, Tully, Cardwell and Ingham. Mission Beach was close to where the storm made landfall. All the yachts at Port Hinchinbrook marina, halfway between Townsville and Cairns, have been destroyed.
Ms Bligh says she has talked to Prime Minister Julia Gillard about relief for cyclone victims.
Food prices are set to rise after the cyclone cut a destructive path through Australia's main fruit and sugar-growing regions. Early indications are that 75% of the nation's banana supply has been affected.
New Zealand's government will wait for an assessment of the damage caused to northern Queensland by cyclone Yasi before it determines what support this country can offer.
Prime Minister John Key says he will call Ms Bligh or Ms Gillard when the extent of the damage is better known. New Zealand stands ready to support Queensland if there is any help it can offer.
As people emerged from homes and evacuation centres to assess the damage, some remarkable tales of survival are coming to light.
The head of Queensland's Red Cross, Greg Goebel, says a decision by a staff member saved the lives of many in the small town of Tully.
"She made the courageous decision last night to move people from the evacuation shelter at the senior citizens' centre into the Red Cross evacuation centre, and this morning the senior citizens' centre had been completely obliterated."
The storm brought winds of up to 290 kilometres an hour a few minutes before midnight. People living in the path of the cyclone described it as sounding like a train roaring overhead.
Geoff Mackley, in Mission Beach, said daylight had revealed a scene of devastation, with trees over the roads and broken glass littering the street.
Tully resident Barry Barnes says most of the houses and businesses in the town' centre are either damaged or destroyed, and many of the area's banana farms have also been destroyed.
Sugar cane farmer Alf Strano barricaded himself inside his house, southeast of Innisfail, and said the huge storm was much worse than Cylcone Larry in 2006. He said the roof of his house had been damaged, power cut and debris was flying everywhere.
Large waves were recorded as the cyclone passed, with one stretch of coast inundated by a storm surge two metres above normal tide level. However, there have been reports that surges were not as severe as feared.
Just south of Townsville, which was being lashed with wild winds and high seas, a wave height of 9.5 metres was recorded.
Further north, Cairns Mayor Val Schier says there are no reports of significant damage, though the weather remains wild.
About 180 thousand homes and businesses from the Whitsundays up to Cairns are without power, and authorities say it may not be restored to some people for several weeks.
Police say they had hundreds of calls for help but were unable to respond due to the dangerous conditions.
Since making landfall the storm progressively weakened. The eye of the storm was 35 kilometres wide as it crossed the coast and the entire cyclone was 500 kilometres wide.