8 dead in Queensland floods

Authorities expect to find more bodies in Queensland communities torn apart by flash floods that have so far killed eight people and left 72 missing.

Dozens of survivors remain stranded in small communities in the Lockyer Valley, west of Brisbane, after it was hit by walls of water that earlier ripped through Toowoomba.

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A massive effort involving defence helicopters is under way to reach people stranded in the devastated towns of Grantham and Murphys Creek, where bodies have been found, and at Withcott.

Atrocious weather is continuing to lash affected communities, and Queenslanders have been told to brace for more deaths.

Premier Anna Bligh said authorities were very concerned about 11 people missing from Murphys Creek, a ravine area that felt the full force of the torrent.

"We are facing some just terribly, terribly sad and tragic stories and I'm very concerned that we're going to see more of those today," she told the Nine Network.

"Mother nature has delivered something terrible in the last 48 hours but there's more to go ..."

• In photos: Australia's flooding worsens  

Queensland's Disaster Co-ordinator Ian Stewart said the toll would almost certainly rise, with 72 people still missing.

"I personally believe it will get worse today, and we are waiting on confirmation from a number of concerning reports," Mr Stewart told the ABC.

"Obviously, our focus now, today, will be to try and help the survivors because we still have a large number of people isolated in the township of Grantham."

Police have confirmed eight deaths so far, including several children. Bodies have been found in the Toowoomba CBD, Murphys Creek and Grantham.

Authorities on Tuesday said all the cars swept away in Toowoomba had been checked and no further fatalities from the CBD area were expected.

Ms Bligh said the scale of the disaster had put emergency services under enormous strain.

Four defence force helicopters have been sent to the flood zone along with extra swift-water rescue experts, Emergency Management Queensland told AAP.

"Right now we have every possible available resource deployed into this region to search for those people that we know are missing," the premier said.

"This is going to be, I think, a very grim day, particularly for the people in that region, and a desperate hour here in Queensland."

More heavy rainfall and possible severe storms are expected in Toowoomba on Tuesday, which is set to further strain rescue efforts.

But Bureau of Meteorology hydrologist Peter Baddeley said the wall of water seen on Monday in Toowoomba and nearby communities was unlikely to be repeated.

More than 50 people remain holed up at a school in Grantham, which looks like a cyclone has swept through it with houses and businesses destroyed and cars wedged in trees.

Grantham resident Christopher Field said the devastation was mind boggling.

"There were houses floating past ...," he told the ABC of the scenes he witnessed at the height of Monday's crisis.

He said historic buildings had been destroyed along with the local pub.

"Grantham shops are being all washed through, cars everywhere in the main street and cars back under the bridge," he said, adding the water had receded but with more rain falling was starting to climb again on Tuesday.

He said there were emotional scenes at the school where residents had taken shelter.

"... I had an elderly man come out and just give me a hug earlier, in tears, he'd lost his house."

Lockyer Valley Mayor Steve Jones said everything possible was being done to help those caught up in the disaster, which has sparked mass evacuations across the valley.

He said an evacuation centre at Gatton was almost full, with others holed up at effectuation points at Grantham, Heildon and Withcott.

The latest ugly chapter in Queensland's flood crisis will dramatically push up a damage bill the premier last week put at about $A5 billion.

Regional Australia Minister Simon Crean said federal cash would continue to flow to communities hit by the "horrific" disaster.

"It's just massive in its scale, it's unrelenting and it's not over," Mr Crean told the ABC.

In Toowoomba, where a woman and boy were killed in the CBD, the scale of the damage from the tsunami-like torrent is extraordinary.

"It was just unprecedented. Some people are saying an inland tsunami, and I think that probably sums it up really," Mayor Peter Taylor told the Seven Network, saying the wall of water arrived without warning.

He said searches were still being conducted in some areas and efforts were also being turned to repairing infrastructure and the clean-up.

"There are buildings in the main CBD area in the lower lying areas that were penetrated by high levels of water, so there's a significant amount of damage ..."

Meanwhile, the flood crisis continues to play out in other parts of the state, with authorities warning of possible flooding in Brisbane city from Wednesday.

The Brisbane City Council has warned about 200 properties could be flooded, most in the areas of Rocklea, Albion, Milton and Auchenflower.

Ms Bligh said the water that fell in the Toowoomba area was expected to move into the catchment of the Wivenhoe dam system that feeds into the Brisbane River.

She said engineers were assessing what that would mean for the dam and the water release strategy into the river.

"The implications of this event are far from over," the premier said.

Overnight, residents in Dalby and Chinchilla were evacuated for the second time in a fortnight.

There was also flooding in Gympie with the water moving down the Mary River towards Maryborough.