'Monster' Cyclone Debbie Batters Northeast Australia

A "monster" cyclone smashed into northeast Australia Tuesday, cutting power, damaging buildings and uprooting trees, with coastal towns in lockdown as residents battled lashing rain and howling winds.

Great Barrier Reef islands popular with foreign tourists were battered by the category four storm which hit the coast of Queensland state with destructive wind gusts of up to 270 kph (167 miles) near its broad core.

There were fears the storm's arrival would coincide with early morning high tides and cause severe flooding, but it slowed before crossing the coastline between the towns of Bowen and Airlie Beach in the early afternoon.

The effects of the storm, which was downgraded to a still powerful category three as it moved over land, were felt across a huge swathe of coast that would span the distance between London and Berlin, although not all areas were badly hit.

"It felt like we were underneath a freight train for most of the night, strong bass rumbles as the... wind rattled past and made the buildings shake," Cameron Berkman, who is holidaying on Hayman Island, told the Australian Broadcasting Corporation.

Queensland politician Mark Ryan said it was also chaotic at Airlie Beach, the mainland holiday gateway to the Whitsunday islands.

"Trees down in Airlie Beach and reports of windows shattering and some roofs starting to cave in," he tweeted.

Queensland Police Commissioner Ian Stewart said there was "certainly structural damage", and at least one person had been badly injured by a collapsing wall.

"I think the public and the community of Queensland need to understand that we are going to get lots of reports of damage and sadly I think we will also receive more reports of injuries, if not deaths," he said. 

The Bureau of Meteorology, which forecast up to 50 centimetres (20 inches) of rain, urged people to stay calm and not be complacent as the eye of the storm passes.

"Do not venture outside if you find yourself in the eye of the cyclone -- very destructive winds from a different direction could resume at any time," it said. 

"People in the path of the very dangerous cyclone should stay calm and remain in a secure shelter."

- 30,000 homes without power -Queensland Premier Annastacia Palaszczuk, who called the storm a "monster" that would last for hours, said at least 30,000 homes were without power with communications down in many areas. 

Conditions have prevented emergency services getting a better picture of damage and they may not be able to do so until first light Wednesday, with the federal government on standby to provide assistance in the aftermath, including with navy helicopters and planes.

Residents, who sandbagged and boarded up homes, had been told to prepare for the worst weather to pummel the state since Cyclone Yasi in 2011, which ripped houses from their foundations and devastated crops.

Yasi, which struck less populated areas, caused damage estimated at Aus$1.4 billion.  Debbie has officially been declared a catastrophe by the Insurance Council of Australia, allowing them to prioritise claims from the disaster.

Some 3,500 people were evacuated between the towns of Home Hill and Proserpine, around 100 kilometres (62 miles) south of Townsville, a tourist hotspot and access point to the Great Barrier Reef.

Another 2,000 people in Bowen also moved, officials said, with cyclone shelters available for those with nowhere else to go. Up to 25,000 more in low-lying parts of Mackay headed to higher ground.

In the small town of Ayr, the main shopping street was deserted with buildings boarded up.

Farmer Anthony Quirk's main concern was for his 150 hectares of mung beans.

"If it comes through here it will be over. It will lay flat on the ground, we won't be harvesting, we will have no crops left," he said.

"It means we start from scratch again. All the money down the drain. That is not good."