Australian authorities have warned residents in Perth's east that they "need to act immediately to survive" as a massive bushfire continues to burn out of control.

Crews are struggling to contain the blaze, which has destroyed at least 70 homes and sent residents fleeing.

Despite the coronavirus lockdown in the region, people have been advised to put their safety first.

"Firefighters are continuing to fight the fire and are protecting life and property within the warning areas," the Department of Fire and Emergency Services (DFES) said.

"People in the warning areas must remain vigilant and keep up to date.

"Protect yourself and your family from the immediate danger of the bushfire first and foremost.

"Whether you are in lockdown or have been personally directed to quarantine for Covid-19, you must do whatever you need to do to keep yourself and your loved ones safe."

Residents have been warned they are in immediate danger as the bushfire rages. The DFES describes conditions as "extreme".

Those in the black shaded Incident Area on the above map have been warned "it's too late to leave and leaving now would be deadly".

More than 200 firefighters have been battling the massive blaze, which started on Monday afternoon and has torn through the town of Wooroloo and affected the shires of Mundaring, Chittering, Northam and the City of Swan.

The blaze has doubled in size and is moving in a west-southwesterly direction. It is out of control and unpredictable. Burning embers are also becoming problematic, starting spot fires up to 100m ahead of the fire.

Strong winds have caused huge problems for crews on the ground and it could be days before the fire is contained. It has so far burned through 9189 hectares. The cause of the fire is unknown.

About 220 firefighters are on the scene. Aerial support has been sent to protect crews and homes.

Emergency warnings in place

Emergency warnings are in place for parts of The Vines, Bailup, Ellenbrook, Gidgegannup, Millendon, Walyunga National Park, Upper Swan, Aveley, Henley Brook, Avon Valley National Park, Red Hill, Belhus, Baskerville, Herne Hill, Bullsbrook, Wooroloo, and Brigadoon in the shires of Mundaring, Chittering, Northam and the City of Swan.

"You are in danger and need to act immediately to survive. There is a threat to lives and homes.

"You need to shelter in your home in a room away from the fire front and make sure you can easily escape.

"You must shelter before the fire arrives, as the extreme heat will kill you well before the flames reach you.

"Close all doors and windows and turn off evaporative air conditioners, but keep water running through the system if possible.

"Choose a room with two exits and water such as a kitchen or laundry.

"If your home catches on fire and the conditions inside become unbearable, you need to get out and go to an area that has already been burned.

"Protect yourself by wearing long sleeves and trousers, made from cotton or wool, and strong leather boots."

Those north of the marked incident area have been advised to travel northwest, away from the fire.

People in the remainder of the emergency warning area have been told to leave now if the way is clear by travelling west-southwest.

WA's Department of Communities has set up three evacuation centres.

'Two different kinds of emergencies'

Western Australia's Premier Mark McGowan yesterday praised fire and emergency authorities for continuing to battle the fire and said the "extremely dangerous" blaze was still threatening homes and lives.

"This is an extremely concerning and serious situation," McGowan said.

"The thoughts of all West Australians are with the people impacted.

"DFES advise they have lost 80 per cent of all properties in the rural area of Tilden Park in Gidgegannup [and] will be conducting inquiries to establish whether there has been any loss of life.

"Right now, WA is battling a dangerous fire emergency and a Covid-19 lockdown emergency."

A number of areas near Perth are also affected by power outages, with at least 2000 homes affected.

Deputy Commissioner at Department of Fire and Emergency Services Craig Waters warned residents: "We're not out of the woods by any shape. We haven't got this fire controlled or contained at this stage.

"It's going to take a huge effort from everyone involved."

The fire has been worsened by weather conditions as wind gusts spread the blaze in the Perth hills, and a large aerial tanker is being brought in from NSW Rural Fire Service to assist.

DFES photographer Evan Collis has taken a series of harrowing photos showing the extent of the disaster on the ground as firefighters battle to contain the flames.