At 4.32am, Fire Rescue Victoria (FRV) responded to an incident on Taunton Drive at Cheltenham after multiple callers to triple-zero (000) reported a building fire.
Firefighters arrived on the scene within seven minutes to find a brick-rendered factory fully involved in fire.
Firefighters donned breathing apparatus to attack the fire, and the response was escalated to a second and then a third alarm.
The fire spread to another nearby building, but firefighters were able to contain the damage caused.
The incident was deemed under control at 6:25am.
The fire has been deemed suspicious and will be investigated by the Arson Squad.
