A factory housing hundreds of cannabis plants has gone up in flames at Springvale overnight.
CFA firefighters were called to the Rosalie Street property after passers-by noticed smoke billowing from the building at 11:30pm on Sunday.
They forced entry and located an "extensive" hydroponic set up with hundreds of semi-mature cannabis plants.
No one was present at the time and it's not immediately clear who is leasing the property.
"I daresay they're probably going to make themselves scarce," said Victoria Police media officer Creina O'Grady.
Police will return to the property, which is under crime-scene guard, and remove the plants from the property on Monday.
Investigators believe an electrical fault sparked the blaze.
The building has been severely damaged and may have to be demolished.