Firefighters responded to a structure fire on Mills Street, Altona North, after callers to triple-0 reported a unit fire.
Fire Rescue Victoria (FRV) crews arrived on scene within five minutes and confirmed that the front unit in a group of three single-storey units on the property was well alight.
Firefighting efforts were initially hampered by the high fuel load at the premises and crews could only attack the fire externally before later entering to conduct a search.
No one was inside.
The incident was deemed under control at 5.19am, but the unit sustained extensive damage.
At the peak of the response, six appliances and 18 firefighters were on scene.
The two adjoining units were unaffected, with all residents accounted for with no reported injuries.
Firefighters remained on scene for several hours to fully extinguish the blaze and monitor hot spots.
The cause of the fire is under investigation.
