Fire crews are on the scene of a fire at ATV Farms on Bathurst Street between Holborn and South Road in Holland Landing. York Regional Police have closed the road.
Multiple fire departments from the area are supplying shuttle tanker services.
NewmarketToday was told the structure on fire is a packing/processing plant.
ATV Farms is a Canadian, family-owned company that packs and ships carrots, potatoes and onions and other root vegetables to retail companies and wholesalers all over the world.
Further details to come as information becomes available.