Photo Courtesy of Syndney Howe via KY 3 TV

Investigators now believe they know what caused a massive explosion that rocked the Kosan Crisplant Propane Facility in Marshfield on the 13th of May.

Eye-witness accounts indicate that a propane cylinder that was dropped, accidentally sparked the fire.

The say it happened near a loading dock where the cylinders were being reconditioned.

The fire took more than 3 hours to get under control and over a day to stop.

More than 10,000 propane tanks in total exploded in the fire.