The Region 5 CFS regional training centre has been destroyed in a $500,000 fire this afternoon (Monday).

Four CFS crews and a bulk water carrier tackled the blaze, which had completely engulfed the breathing apparatus training shed at Wild Dog Valley, north of Naracoorte.

The structure and contents were completely destroyed, however other buildings on the property were saved by the volunteers.

Crews will remain on scene this afternoon to mop up and make the area safe.

No cause has yet been determined and fire cause investigators will inspect the scene tomorrow (Tuesday).