Toronto police say they discovered a marijuana grow operation inside a Scarborough home that burst into flames overnight.

Toronto Fire Services were called to the scene in the Sheppard Avenue and McCowan Road area at about 11 p.m. Wednesday night.

It took five hours to put out the two-alarm fire. At the height of the fire, 80 firefighters were on the scene.

It wasn't until the flames were put out that firefighters could enter the home and investigate. That's when they found the large operation.

Fire Capt. Mike Strapko told CTV Toronto it was an elaborate set up.

"We got three water hose lines connected to part of the heating and humidifying unit," he said. "They tapped into the electrical down below and that is why Toronto Hydro is out at street level now disconnecting the power. If firefighters were to go down there now, there's a good chance they could be electrocuted."

Propane tanks were found on the property but Strapko said it's too early to determine what caused the fire.

No one was living in the house, police say. However, residents living in neighbouring homes were forced to seek shelter in a TTC bus while firefighters battled the blaze.

Police say they are looking into the matter. No charges have been laid.

With a report from CTV Toronto's Austin Delaney