Officials say they are battling against the worst fire conditions in the state's history.
Six people have been killed in the township of Kinglake, four at Wandong, three at Strathewen and one at Clonbinane - all in Victoria state.
In Kinglake, north-west of Melbourne, one resident said the whole township was pretty much ablaze and that the fire front came through in a matter of minutes.
He said that some 200 residents had taken refuge in a local pub and that no fire engines could get into the town.
Tens of thousands of firefighters are trying to contain blazes in two further states - New South Wales and South Australia - but blazes there were largely contained or burning away from residential areas.
However if winds pick up, the authorities fear that the fires could spread.
The fire service is using water-bombing aircraft to contain fires. Thousands of volunteers are using water hoses.
"It's just going to be, probably by a long way, the worst day ever in the history of the state in terms of temperatures and winds," Victoria Premier John Brumby said.
"It is extremely dry. We do have some concern about the winds winds picking up and having an impact on the fire," a spokesman for Victoria state's Country Fire Authority told Reuters.
In 1983, a wildfire killed 75 people, on a day known as Ash Wednesday.
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