The scale of the carnage, growing daily, has shocked a nation that endures deadly firestorms every few years. There were no quick answers, but officials said panic and the freight-train speed of the firefront probably accounted for the unusually high toll.

Prime Minister Kevin Rudd, visibly upset during a television interview, reflected the country's disgust at the idea that arsonists may have set some of the 400 fires that devastated Victoria state, or helped them jump containment lines.

"What do you say about anyone like that?" Rudd said. "There's no words to describe it, other than it's mass murder."

At least 750 homes have been destroyed across the state, and 3,733 people have registered with the Red Cross after evacuating their properties. The number left homeless is expected to be far higher, the Red Cross said.

It was confirmed that at least four children have died, but that figure would also be expected to rise as full details emerged.