Five firefighters injured in western Victoria as residents near Grampians National Park told it's too late to leave

Five firefighters have been injured battling blazes in Victoria's west as residents take shelter after being told it is too late to leave.

Five members of the Country Fire Authority were in a vehicle "involved in a burnover while on the fireground" at Pomonal, near the Grampians National Park, this afternoon.

All five were assessed by paramedics, the CFA said.

READ MORE: Greens MP in hospital after serious car crash in Brisbane

Hundreds of firefighters are on the ground as crews battle out-of-control blazes in extreme conditions.

A catastrophic fire warning was issued for communities in the west as temperatures neared 40 degrees, while the rest of the state remained on watch.

Multiple fires were this afternoon burning out of control , with two major fires taking hold in the Grampians National Park.

The State Control Centre earlier issued a warning to residents near the national park, urging people to leave immediately, before advising it was now "too late" to leave.

Residents at Dadswells Bridge, Roses Gap, Ledcourt, and at Pomonal, Bellfield and Lake Fyans were told it was too late to leave if they hadn't already evacuated.

The communities are near the major township of Stawell.

The CFA this evening confirmed that homes had been lost at Pomonal, but it was unknown exactly how many.

Residents were earlier told to evacuate to nearby Ararat and travel on the Ararat Halls Gap Road.

The major fires are believed to have been ignited by lightning strikes from early morning storms.

Winds of up to 130km/h helped to fan the fires.

Victorian resident Noah and his father had decided to stay and defend their property at Pomonal.

But this afternoon the decision was taken out of their hands when firefighters turned up to the property.

"It wasn't so much of a worry today and then they said we better leave and then they said, 'No seriously, get out'," Noah told 9News.

"We built this house only a few years ago so just really want to save it."

CFA chief officer Jason Heffernan said the two major fires at Bellfield and Mount Stapleton were causing significant concern.

"We're not out of the woods yet, we do expect strong winds to continue to move through and that will dramatically change the directions of those fires," Heffernan said.

"There are many communities at risk and the situation is very dynamic."

West of Ballarat, firefighters were battling a fire near Beaufort which was threatening communities.

Communities in and around Grampians Junction, Lake Goldsmith and Oitfield Plains have been warned to keep an eye on the conditions, with multiple fires burning in the area.

It comes after dire warnings from the state's emergency management authorities, who predicted hot, dry and windy conditions paired with thunderstorms would spark dangerous fires across the state.

Images posted from the scene to social media have shown big plumes of smoke fill the air, while thick, dark clouds filled the sky.

Extremely hot, dry and windy conditions hit most of the state.

Extreme fire danger warnings are in place for the Mallee, Northern Country, and Central districts.

Kevin Parkin from the Bureau of Meteorology warned it would be the first time since November 2019 that the state experienced such dangerous conditions.

READ MORE: Hawkers craft beer enters voluntary administration

"I've been in this game for a number of years and these conditions are the worst I've seen since the 2019-2020 summer fire season," Parkin said.

Temperatures reached into the high 30s and low 40s across Victoria paired with dry and extremely windy conditions.

READ MORE: 'Still hope': Search for Victorian mum Samantha Murphy enters eighth day

Total fire bans were in place across the state.

The state's regional train service, VLine, also reduced timetables on the Bendigo, Echuca and Swan Hill train lines.

Chris Hardman from Forest Fire Management Victoria said fire conditions on catastrophic days could be "uncontrollable and fast-moving".

"Do not visit parks and forests and if you're there, get out tonight," he said.

"It's really important that people don't visit, particularly in those areas in the Wimmera.

"If fires start in those areas, they can quickly become uncontrollable and your life will be in danger."

READ MORE: Energy giant Santos expands nine-day fortnight program for workers

Fire crews were on standby across the state and water-bombing aircraft will be placed in strategically-located areas.

Authorities have warned power outages may happen and have urged people to keep an eye on the Vic Emergency app, as well as their emergency broadcaster.

CFA chief officer Jason Heffernan said the conditions were among "some of the worst" firefighters had ever seen.

"We're calling communities to be aware of conditions tomorrow," he said.

Emergency warnings can be followed via the Vic Emergency website and app.