A barn housing a large medical marijuana grow operation has been completely gutted by fire.

The property, licensed to grow medical marijuana, is an area near lots of dairy farms.

Flames broke out around 10 p.m. Sunday night and could be seen from several kilometres away.

More than 40 firefighters were called to the scene to battle the blaze, which was worsened by wind.

The cause of the fire is still unknown and investigators say it could be a few days before investigators figure out what started the blaze.