The first crews arrived at the paint factory on Superior Drive in Dandenong shortly after midday on Friday and immediately called for back-up.
Police and paramedics were also called to help evacuate and treat workers amid reports of multiple explosions at the site.
Advice - Industrial Fire at Superior Dr, Dandenong South. Threat is Reduced. For more info: — VicEmergency (@vicemergency) https://t.co/uX31QorwZY #vicfiresDecember 8, 2023
A man in his 60s was taken to The Alfred Hospital in a stable condition with upper body injuries, while two other men in their 30s and 40s were taken to Dandenong Hospital.
Both were in a stable condition with upper body injuries, Ambulance Victoria said.
Another person was transported to The Alfred.
One factory worker was missing, Fire Rescue Victoria said in a statement.
More than 120 firefighters and 40 trucks remain on the scene trying to get the massive blaze, which has been burning for hours, under control.
Smoke remains visible several kilometres away from the blaze. (HANDOUT/SES VICTORIA/FACEBOOK)
Smoke remains visible several kilometres away from the blaze with strong winds blowing smoke across the area.
Authorities downgraded a watch and act warning to advice for local resident after the fire threat was reduced.
Fire Rescue Victoria assistant chief fire officer Greg Chistison said the winds were quite extreme.
"It's presenting a number of challenges for us in suppression activities," he told reporters.
"But we've got a large resourcing commitment on the fire and we're quite comfortable at this stage that we're making good progress on the fire."
Several roads in the area were closed and drivers warned to avoid the area.
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