A man has been charged after a woman was rushed to hospital with burns to 38 per cent of her body after she was allegedly set on fire, before a car exploded in Perth's outer-east.

Police were called to reports of a car on fire near the corner of Honey St and Mill End in Mount Helena, about 35km east of Perth's CBD, about 6.25pm Friday.

Witnesses nearby heard multiple explosions before police found a blue Holden Commodore on fire and two people suffering burns.

Neighbours told Nine News a woman was seen running about 100m from the scene, screaming and on fire while tearing clothes off her body, meu before they rushed to help.

The RAC Rescue Helicopter was needed to fly the 33-year-old woman to Fiona Stanley Hospital with partial-thickness burns, also known as third-degree burns, to 38 per cent of her body - including her face.

Meanwhile, the woman's 42-year-old recently separated ex-husband was taken to the same hospital by St John Ambulance with superficial burns.

WA Police on Sunday said the man has been charged with aggravated grievous bodily harm.

He was taken into custody shortly after being discharged from hospital, and is due before Perth Magistrates Court on Sunday.

WA Police Inspector Glen Beros told media on Saturday the incident is tragic.

'A young woman has got significant burns to her body, which is going to take a long time to treat, and then the rest of her life will be impacted by that,' Inspector Beros said.

'The investigation is still in its infancy, however, they were in a family relationship, and there was violence.'

Anyone with information regarding the incident should call Crime Stoppers on 1800 333 000, or make a report online.

If you or someone you know is experiencing domestic violence, you can get help by calling 1800 RESPECT (1800 737 732).