The destructive eyewall of Cyclone Debbie, a Category 4 storm packing winds up to 260 kilometers per hour (160 miles per hour), made landfall near Airlie Beach, a resort town in Queensland state, the Australian Bureau of Meteorology said in a statement.
Wind gusts of 262 kmh, the highest during the storm, were recorded on Hamilton Island, so it was expected to be hit hard, although its resorts were created to withstand category 5 storms.
A man, believed to be aged in his 60s, was badly injured when a wall collapsed on him in Proserpine.
Its slow, potent march inland had officials fearing widespread damage, but the loss of telephone service and power left emergency responders struggling to assess the situation.
"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", Commissioner Stewart said.
"The trees are going wild", the man, identified only as Charlie, told the Australian Broadcasting Corp.
State Recovery Co-ordinator Brigadier Chris Field, who co-ordinated clean-up efforts following Cyclone Yasi in Queensland in 2011, will lead recovery efforts.
"It's very noisy: Screaming, howling wind. sounds like a freight train", Jan Clifford told Reuters by text from Airlie Beach as the cyclone made landfall.
Heavy rain and damaging winds are said to continue thrashing Queensland for hours to come, as locals digest the extent of the damage.
Cyclone Debbie has wrought havoc and devastation across the north coast of Australia.
Qantas, Jetstar and Virgin Australia suspended flights to and from the region and said planes may also be grounded on Wednesday, although Townsville airport said it would reopen. The storm halted at least 20 percent of coal output from the biggest producing basin in Queensland, with BHP Billiton Ltd. and Glencore Plc suspending operations.
"We do know that hundreds of hectares of sugarcane has been flattened by cyclone Debbie's winds with the Mackay and Proserpine districts the worst affected", Canegrowers CEO Dan Galligan said.
The town is a jumping-off point for the Whitsunday Islands, a popular tourist destination that has been pummeled by fierce winds that damaged roofs and knocked down palm trees.
Holidaymakers tried to make the best of it as they bunkered down in resort buildings.
"I'm so anxious. I can't remember exactly but he said something like "I'm not going to win this one", she said.
"I'm so glad we got evacuated out of the place we were staying at, I think we'd be pooping watermelons right now to be honest", he said.
Despite issuing evacuation orders, police said they were not sure how many people had heeded their advice.
That did not deter some thrill-seeking bodyboarders who paddled out to surf in the heaving seas at Airlie Beach, television footage showed.