A week-long heatwave has caused havoc in southern Australia, where bushfires have destroyed up to ten homes, weather records have been broken, and up to 19 people, many elderly, have died during soaring temperatures averaging over 40C (104F).

In what the weather bureau has described as "Black Friday", bushfires are burning across the east of the southern state of Victoria, which today endured a high of 45.1C, its record-breaking third consecutive day above 43C.

The bushfires – two blazes that combined after wiping out a timber plantation at the town of Boolarra in the Latrobe Valley to the east of Melbourne – have so far destroyed a reported ten homes and burned through more than 2,260 hectares.

Five hundred firefighters have tried to hold back the blazes over the past 24 hours but they are still burning.

"Everybody is under threat … we are in deep s***," one resident controller warned the people of Boolarra during a town meeting where residents were told to activate bushfire emergency plans or face dire consequences.

The town has reportedly already run out of water due to the extra demand.

One Boolarra resident, named Laura, has lost her home and told the Australian Broadcasting Corporation that many more on her street were also gone.

"The main thing is we've got each other, and we've got our one-year-old, and we got out and got our pets out, but I know a lot of people weren't that lucky," she said.

"Three [houses] definitely, that my husband saw were gone, but other than that, I just don't know."

Melbourne and Adelaide were disrupted by power blackouts as millions of overheated people switched on air conditioners, and commuters faced lengthy transport delays as train and tram lines buckled in the heat.

In Adelaide 19, mainly elderly, people are reported to have died during the heatwave, a higher than average daily figure of sudden deaths. Only two sudden deaths were recorded last Friday.

John Hill, the South Australian Health Minister, would not confirm whether the deaths were heat-related, but acknowledged that the increase was high.

"How many of them are associated with the heat is speculative – but it's obviously a high number," he told the Adelaide Advertiser.

Even the tennis players at the Australian Open couldn’t escape the heat. On Tuesday Novak Djokovic, the men’s No 3 seed, retired ill from a game after heat-related complaints that have dogged tournament organisers all week, and the retractable roofs on Rod Laver Arena have been closed for part of the past three days.

The heatwave has also affected Tasmania, traditionally Australia’s coolest state, which reached 42.2C at Scamander – an all-time record for the island.

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