Four devastating ''fire whirls'' have ripped through a pastoral property near the Kimberley town of Fitzroy Crossing, tearing trees from the ground and amazing those who witnessed them.

The whirls, described as being as high as 300 metres, formed during a blaze that scorched three million hectares in the region.

Staff at the Leopold Downs station said the whirls sounded like an approaching truck.

The general manager of the Eastern Gurama Pastoral Company, Mr Richard Paterson, described the whirls as extraordinary.

"We heard this rumble, as the fire was coming across," Mr Paterson said.

"We thought it sounded like someone was bringing an empty road train down the road, it was that loud.

"And then when the truck didn't turn up we sort of drove down there and you could see this starting to form.''

Mr Paterson saw four fire whirls cross the road in front of him. They even tore trees out of the ground, Mr Paterson said.

"It just ripped the fire straight across the road in front of us," he said.

"They were extraordinary. We had a helicopter in the air, the pilot estimates it was about 1000 feet high. And they would have been 200 metres across where they crossed the road. They were extraordinary.

''I've never seen anything like it."

Dangerous and unpredictable

Fire whirls are a rotating vortex on a fire front and they typically contain flames, said fire weather researcher for Bureau of Meteorology Mika Peace.

Destructive force: A fire whirl on Leopold Downs station in the Kimberley. ( Richard Paterson )

"They can range from less than a metre to three kilometres across and the winds in fire whirls winds can reach 50 metres per second," she said.

"Fire whirls are frequently reported at fires, they vary in size and longevity."

The perfect conditions for a fire whirl include calm or light to moderate winds, lee slopes, heavy fuels and unstable atmospheres.

"They can be very dangerous and unpredictable in motion," Ms Peace said.

Blustery conditions

More than three million hectares — an area the size of Belgium — burned in fires across the Kimberley over the West Australian long weekend.

Leopold Downs station has been considered the worst hit, with 90 per cent of the property lost in the fire.

"We must have lost 400,000 hectares just on Leopold," Mr Paterson said.

"There was just nothing left. She was a pretty hot fire even at night. In one night alone it moved about 30 kilometres and jumped a track overnight as well, so it was burning pretty hot the whole time."

The bushfire that formed the fire whirls destroyed up to three million hectares across the Kimberley WA long weekend. ( My Fire Watch )

The fire has had a major impact on the pastoral business, Mr Paterson said. Property and cattle had been destroyed, so the station won't be able to "fully re-stock' in the next year.

"There's just nothing left in that back valley where those cattle are."

"There's only about 1,000 head left on there, but they're going to have to muster those I think to bring them forward on to the feed."

Fire treated as suspicious

Mr Paterson said there had already been too many fires in the region for the time of year.

"Gutted, absolutely gutted especially because we believe it was deliberately lit," he said.

"It's not lightning strikes that are doing it, whether people are doing it for hunting. I know there's one fire that got away from campfires and that sort of stuff. But just be really careful.

"The winds are back, they're pretty strong and it just gets away so quickly.

On Tuesday, nine fires remained on DFES's system, with a number of other beings monitored, said Department of Fire and Emergency Services (DFES) superintendent of the Kimberley region Rick Darlow.

"Some of the pastoralists are struggling," he said.

DFES are treating the fires at Leopold Downs station as suspicious.