Fire and Emergency New Zealand investigators and police were on site yesterday working to determine the cause.
The alarm was raised just after 4am. The Hokitika Volunteer Fire Brigade was alerted that one person had escaped but another might be inside.
The house bus was located up a gravel driveway beside the Hokitika Pistol Club range and was not visible from the road.
Fire chief Peter Cuff said the brigade arrived to find the bus well alight.
"Unfortunately, one person was found deceased on the scene."
Two appliances from Hokitika, the Kokatahi-Kowhitirangi brigade and the Cobden brigade's water tanker spent nearly three hours extinguishing the flames.
St John attended, and the Roa Mining West Coast Rescue Helicopter was called but turned back.
