A man has been seriously burnt and a vineyard at a winery has been destroyed, while hundreds of people have taken refuge at two evacuation centres as a bushfire ravages an area south of Perth.
The man in his early 20s was burnt on his upper torso while battling the blaze near Waroona and was flown to Perth for treatment on Thursday afternoon, a St John Ambulance spokesman told AAP.
It is not clear whether he is a firefighter.
Nine patients from Harvey Hospital were evacuated to other hospitals, the spokesman said.
Drakesbrook Fine Wines owner Bernie Worthington said his vineyard, olive grove and orchard were destroyed, but amazingly his 17 rescue chooks and goats survived.
An emergency warning remains for Waroona, Harvey and surrounding areas including Preston Beach in Western Australia's Peel and South West regions.
The Department of Fire and Emergency Services warns lives and homes are in danger from the fast-moving and out-of-control blaze, and burning embers are likely to be blown around homes.
Melissa Young lives on a 90-hectare property about 12 kilometres out of Waroona and was forced to evacuate with her dog on Wednesday night.
"I watched this amazing, ferocious thing. The speed was insane, it engulfed everything," she told AAP.
There were also reports of some people being evacuated from Preston Beach by boat.
About 170 people have registered with the evacuation centre at Murray Leisure Centre in Pinjarra.
Another 80 people sought shelter at a second evacuation centre in Harvey, but that was moved to Australind when the fire spread.
Residents have been told they are not likely to be able to return home for at least three days.
Department for Child Protection and Family Services director general Emma White said if it was safe, people should bring essential documents, medications, jewellery, photos, clothing, a mobile phone and charger with them.
An emergency relocation kit with sleeping bags, towels, toiletries, cash and games to occupy children were also handy, she said.
Pets cannot be accommodated inside the evacuation centres, but the Shire of Murray is helping residents with animal welfare.
Federal MP Andrew Hastie and state MP Murray Cowper both met with residents to offer their support.
The blaze started in Lane Poole Reserve and is burning on both sides of the South Western Highway, with several roads and recreation sites closed in the area.
Meanwhile, a watch and act alert remains for people in an area bounded by Johnston Rd, Willowdale Rd, Forrest Highway, Riverdale Rd and Logue Brook Dam, and Clarke Rd to Nanga Rd, in the Shire of Waroona.
Western Power says more than 7000 customers are without power and crews cannot access the area to assess any damage to the network.
It warns if the bushfire has damaged power poles and lines, some customers may be without power until the area is safe for crews to start rebuilding the electricity network.
The temperature got close to 40C and the Bureau of Meteorology has forecast gusty winds in the evening.
"The possible development of thunderstorms in the area is another complicating factor, and there is a risk of lightning strikes which may cause new ignition points," the bureau said.
The fire, sparked by lightning, was reported just before 7.30am on Wednesday and has burnt more than 21,000 hectares.
Waroona had a large bushfire sparked by lightning early last year too, with one home and several sheds, cars and equipment destroyed in that blaze.
The Waroona and Harbey bushfire - what you need to know
Preston Beach and east of South Western Highway
- Emergency warning
- Too late to leave
- People must shelter in their homes and actively defend them
West of South Western Highway, including Harvey
- Emergency warning
- People can evacuate in a westerly direction
- Beware of continued ember attacks
- More than 21,000 hectares burnt
- Fire first reported 7.25am, Wednesday
- Caused by lightning
- One man taken to hospital with burns to his back
- More than 7000 properties without power
- Several recreation sites closed
- More than 200 firefighters
- Aerial support assisting firefighters on the ground
- More than 23 appliances, including five dozers and three loaders, to establish containment lines
- Evacuation centres at Murray Leisure Centre and Leschenault Leisure Centre
- Temperature reached 40C on Thursday
- Bureau of Meteorology forecasts similar hot and windy conditions for the rest of the week
- Thunderstorms also possible