Investigators say a fire in Ellsworth was caused by an exploding propane tank on an old school bus that had been converted into an RV.

The fire was reported around 3 p.m. Tuesday on North Street, where investigators say an electric component in a nearby fridge likely ignited a leak from the propane tank.

An investigation found that the explosion originated in a cabinet under the propane range.

The sole occupant in the vehicle suffered serious burns and was taken to Northern Light Maine Coast Hospital.

The fire is under investigation.