Mystery surrounds a late-night house fire in Perth’s north east that triggered a major emergency response.

Crews were called to the home on Burton Retreat in Stratton, in the city of Swan, about 11.30pm after receiving reports of a blaze.

The home’s occupants fled the home before it was engulfed.

Photos at the scene showed extensive damage inside the home.

Police say its not known what sparked the inferno.

Officers will return to the scene on Tuesday to conduct further assessment.