Sirens wailed across Australia's third-largest city, Brisbane, on Wednesday, warning those remaining in the mostly deserted central city that deadly floodwaters had arrived.
Muddy waters reached to the top of traffic lights in some parts of the city, following evacuation efforts that sent many residents fleeing to higher ground.
Officials say floodwaters from the swollen Brisbane River - which cuts through the heart of the city-- have already killed at least 22 people since last month. They expect the death toll to rise now that flooding has hit the Queensland state capital.
Brisbane Mayor Campbell Newsome says nearly 20,000 homes will be flooded by Thursday, when the river is expected to crest. The raging waters have already torn boats away from their moorings and sent them floating aimlessly through the city. Australian Prime Minister Julia Gillard has called the disaster "mind-boggling."
More than 40 cities and towns in Queensland have been submerged since late December by torrential rains from a disruptive weather pattern known as La Nina. More than 200,000 people have been affected by the flooding, which forecasters say is among the worst in the past century.
Earlier this week, a flash flood washed over the northeastern town of Toowomba, killing 12 people, but Queensland Premier Anna Bligh said Wednesday the number of missing had fallen to 43.
The high water has also cut road and rail lines, damaged farmland and virtually shut down the state's major industry, coal mining. The cost of the recovery is expected to reach into the billions of dollars.
On Wednesday, British Prime Minister David Cameron told her Britain was ready to offer any needed assistance.
Some information for this report was provided by AFP and Reuters.