Thousands of people in the Australian state of Tasmania are stranded and roads are cut off as three wildfires are burning out of control.

Towns along the east coast and the central part of the state are threatened by the fires.

The fires scorched a large swath of land all the way to the waterline and some residents and tourists had to wade into the sea to escape the fire, which has either damaged or destroyed at least 100 homes, businesses and a school.

The worst hit area is around the small town of Dunalley, east of the Tasmanian capital of Hobart, where 65 buildings including the town's school, police station and bakery were destroyed, local media reported.

Officials had been investigating a report that one person died in the blaze yesterday, but police said there were no confirmed deaths or injuries from the fire.

The island state's fire service has issued emergency warnings and officials said it would be a while before the fires are contained.

"Clearly, it's going to take a long time and a lot of work to properly contain these fires. So, people have to be still aware there is a risk and still keep themselves abreast of the latest information," Chief Officer Mike Brown of the Tasmanian Fire Service told reporters.

Some of the stranded tourists who spent the night in the historic Port Arthur, a former prison colony, were evacuated by ferry to Hobart.

"(It) was very unpleasant because it was really hot and then the smoke came over very thickly and it's full of debris and made me realise it was very close," said one evacuee after disembarking the rescue ferry.

Wildfires raged across southern Australia amid blistering temperatures and high winds.

The temperature in Hobart reached a record high of nearly 42C yesterday.

Conditions had eased across much of the region on Saturday, but fire officials warned that the danger from some of the fires remained high.

Wildfires are common during the Australian summer.

In February 2009, hundreds of fires across the southern state of Victoria killed 173 people and destroyed more than 2,000 homes.