The roof of the building has been destroyed by the flames.
Three people have been released on bail after they were arrested on suspicion of cultivating cannabis.
Emergency services were sent to a building fire on the Station Road/ Equity Road junction in Earl Shilton at 02:20 on the 22nd of May.
Leicestershire Police said: "Officers were called to the location by the Leicestershire Fire and Rescue Service around 3.30 am yesterday (Monday 22 May) after they discovered some cannabis plants in the property while they were dealing with a fire.
"The men, aged 32, 40 and 65, have been arrested on suspicion of cultivating cannabis. They have since been released on bail pending further enquiries.
"The investigation is ongoing and if anyone has any information they are asked to contact 101 or report via www.leics.police.uk, quoting crime number 23*308786."
Appliances from Hinckley, Market Bosworth, Southern, Western, Wigston and Birstall’s Aerial Ladder Platform (ALP) were all sent to the scene.
Leicestershire Fire and Rescue Service have said that the cause of the fire was accidental.