Ten-bedroom family home goes up in flames in north-west Sydney

A 10-bedroom house in north-west Sydney has likely been destroyed by a fire thought to have possibly been started by a lightning strike.

Eleven fire trucks and more than 70 firefighters were sent to battle the blaze on Cattai Ridge Road in Glenorie, in the Hills District.

The fire broke out about 7.30pm on Wednesday and the family home was fully engulfed when Rural Fire Service, Fire and Rescue NSW, NSW Police Force and NSW Ambulance crews arrived on scene.

Vision showed flames and fire-tinged smoke pouring into the sky above the large one-storey building.

The family-of-seven living in the home managed to get themselves out uninjured and spent the night sheltering down the road.

It took firefighters hours to bring the blaze under control but they were eventually aided by rain that returned late on Wednesday.

Matthew Lloyd from the NSW RFS said crews had to stop any work inside the building "fairly quickly" thanks to flames inside and the roof collapsing.

"It was burning quite hot," he said.

"It was a fairly significant fire that extended throughout the roof cavity.

"So unfortunately, despite the good work or the careers it's probably a total loss."

Locals and the family believe a lightning strike when the storm front first rolled through may have started the fire.