A "gut-wrenching" clean-up was in full swing Monday as floodwaters receded across parts of Australia, with fears the death toll could rise after a car was swept into a swollen river.

At least two people were confirmed killed after cyclone-fuelled rain and winds pummelled swathes of Queensland and New South Wales over the past week, forcing the evacuation of tens of thousands of people and causing hundreds of millions of dollars worth of damage. 

Six people are missing, including three who were feared dead Monday after a car plunged into the Tweed River in northern New South Wales. A young girl managed to escape but three others -- believed to be a mother and her two children -- had not been found.

"A police operation is underway to recover the three occupants of a vehicle that entered the Tweed River, near Tumbulgum, this afternoon," police said.

While the worst of the weather is over as  Cyclone Debbie moved out to sea on Saturday, the daunting task facing those affected is just beginning with residents returning to thick mud and ruined property. 

New South Wales State Emergency Services Deputy Commissioner Mark Morrow said it would be a long haul for towns such as Lismore and Murwillumbah that were inundated by floods.

"The mud, combination of chemicals, raw sewage, paint which gets into everything. Two to three metres above floor level. Nothing escaped this. It was a very, very big flood," he said.

Many of those who fled the area have begun heading back, with Morrow warning "it won't be pleasant". 

"It will be a lot of work for those people as they return today," he said.

The Insurance Council of Australia has estimated the damage bill could reach Aus$1 billion (US$770 million), as people braved mud-caked streets to begin clearing out homes and shops, with mountains of ruined possessions piled on pavements.Military and emergency personnel continued to work to restore essential services such as water and electricity in affected towns, where hundreds of homes have been deemed uninhabitable.

Adding to their worries was the fear of looting, with New South Wales police charging one man with theft and moving on 16 more who were "acting suspiciously".

Prime Minister Malcolm Turnbull said seeing the damage up close was heart-breaking, as he toured Lismore.   

"Seeing it first-hand and the impact, treasured possessions, all of a life's work, all of the assets of a business flung out onto the pavement -- that is gut-wrenching stuff," he said.

- 'Not out of the woods' -

The cyclone dumped more than a metre of rain on parts of Queensland and the huge volume of water is still slowly spilling down river systems, with Rockhampton next in the firing line.

It was feared the town would be hit later this week by its worst flooding in more than 60 years, but authorities Monday said the estimated peak had now been revised down, although major flood warnings still exist.

"We do want to stress to the people of Rockhampton that you still need to make your flood preparations," said Queensland Premier Annastacia Palaszczuk.

"We are not out of the woods yet, there is still a long way to go," she added, stressing that 300 schools in the state had been damaged and needed repairs.

One of the worst hit areas was Airlie Beach and the Whitsunday Islands, key foreign tourists draws.

Many resorts face months of repairs and rebuilding, but tour boats mostly survived and some are already back in business.

"I've got butterflies being back on the water," tour operator Asher Telford told the Australian Broadcasting Corporation as he set sail with 18 undeterred holiday-makers on a two-night cruise.

Queensland Tourism Minister Kate Jones said the lucrative industry would bounce back, stressing "Queensland is still open for business".

source: AFP