Firefighters battled a blaze at an outbuilding in the Ribble Valley village after gas cylinders caught fire.
Crews from Blackburn were called to Saccary Lane, Mellor, just before 9 am on Wednesday to extinguish the fire.
A spokesman for Lancashire Fire and Rescue confirmed an investigation was under way.
He said: "The fire was extinguished using hose reel jets. Although the gas cylinders caught fire, there were no casualties. An investigation is under way."