The state fire marshal's office says has ruled the cause of an explosion at a grain elevator in Northrop as accidental.

59 fire departments responded to the December 28 explosion.

In the investigation report, the state fire marshal called the incident a dust explosion, with a subsequent fire. Investigators were unable to fully determine what caused the explosion, though a small ticking noise in the equipment could be what created a spark that ignited it.

The fire marshal says that because the ignition source could not be confirmed, the cause will remain listed as undetermined.

--KEYC News 12