UPDATED 3.35pm: A fire at a West Auckland building was swiftly put out but the cause of the blaze is under investigation.

Six firefighters were called to the scene of the fire on Henderson Valley Road just after two and the fire was put out half an hour later.

The single-storey building was unoccupied but was in an area where there are several film studios.

Northern fire communications shift manager Scott Osmond says it appears to have started inside the building.

He says the cause is still unknown but fire crews are investigating.