Thousands of Victorians face “days or weeks” without power after extreme storms near Melbourne left 500,000 properties in the dark on Tuesday afternoon.

Transmission towers collapsed, transmission lines tripped and multiple generators were knocked out at the state’s largest coal-fired power plant Loy Yang.

The extraordinary weather brought down hundreds of power poles and lines in what state Energy Minister Lily D’Ambrosio said was “one of the largest outage events in the state’s history”.

“The wild weather resulted in the physical collapse of six transmission towers near Anakie on Tuesday afternoon,” the Victorian Department of Energy, Environment and Climate Action said on Wednesday.

“Concurrently, the Loy Yang A power station tripped and was disconnected from the grid, leading to the Australian Energy Market Operator enacting load shedding to keep the power system secure.”

Six transmission towers collapsed at Anakie. Photo: Jacqui Felgate

On Wednesday morning there were still 280,000 properties without power.

As of 9pm on Tuesday, more than 470,000 customers were affected, down from 530,000 earlier.

The DEEAC said it might take “days if not weeks” to restore electricity given the extent of the widespread damage.

The Loy Yang A power station is also still being reconnected to the grid.

Some Victorians were told by their providers they may be without power until Thursday.

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Power expert Professor Bruce Mountain told the ABC it appeared to be the worst damage to Victoria’s transmission system in the state’s history.

He said the state faced “quite a stressful situation” in coming weeks.

“The big coal-fired generator was knocked off the system from this. It’s been restored partially. We’ve seen some energy production from it last night, but not yet fully,” the director of the Victoria Energy Policy Centre said.

“We expect to be relying a great deal on gas.”

The pivot to gas, and wind, could drive up short-term spot prices, he warned. But most customers wouldn’t be affected.

‘Couldn’t believe it’

As storms slammed Melbourne, bushfires were encroaching on towns near the Grampians National Park.

Homes were destroyed at Pomonal, in Victoria’s west, and five firefighters suffered injuries when the fire front passed over them.

Authorities are still working out how many homes have been destroyed in the fires in Pomonal, which have burned through about 2000 hectares.

Northern Grampians Shire Mayor Rob Haswell said people who fled Pomonal were shocked at how quickly the fire swept their town.

“They couldn’t believe it. They couldn’t believe how quick that fire, that went from seeming like a hot and windy afternoon to suddenly fire all around them. It was very, very quick,” he said on ABC TV.

He said people who made it safely to a relief centre “were sitting quietly and just staring in space”.

“Horrible, horrible thing to witness people in a state of shock like that.”

People in Newtown near Ballarat were ordered to evacuate on Tuesday night after a grassfire spread into a forest and morphed into a bushfire.

Those near the Mount Stapylton and Bellfield areas in the Grampians National Park were ordered to stay in place and seek shelter on Tuesday afternoon after out-of-control flames raged.

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Five country firefighters suffered minor injuries after their truck was involved in a burnover at a fireground at Pomonal.

The team of firefighters had been pre-positioned in the town to protect homes and critical infrastructure.

“When the wind change came through, the fire moved very rapidly into Pomonal and those firefighters were caught between the fire front and the work they were doing in protecting communities,” Forest Fire Management Victoria chief Chris Hardman told ABC News.

Impact assessment teams will be in the firegrounds on Wednesday to assess any loss of life and damage to properties.

The fires and power outages came after Victoria sweltered through three days of heat, with temperatures topping 40 degrees in some areas on Tuesday.

Dry lightning strikes mixed with wind gusts reaching 100km/h fanned the out-of-control flames.

Temperatures will drop following a cool change on Wednesday but fire conditions are expected to persist.

-with AAP