Residents near a large factory fire burning out of control in Melbourne have been urged to immediately take shelter indoors, with thick black smoke billowing into the air.
Witnesses have described explosions during the blaze on Thornycroft Street in Campbellfield, which ignited about 6.40am on Friday.
About 80 firefighters are battling the fire, which is sending thick black smoke towards the CBD.
A witness from the nearby suburb of Wollert, Dave, told 3AW radio he saw a "massive explosion that looked like a mushroom cloud".
A watch and act message has been posted by emergency services urging people to avoid the area.
"Anyone located in Broadmeadows, Pascoe Vale , Coburg should take shelter indoors immediately," it says.
People in those areas are being told to stay indoors and ensure all exterior doors, windows and vents are turned closed and heating and cooling systems are turned off.
Crews found the 30-metre by 30-metre factory fully alight on arrival and quickly called for enforcements, authorities said.
It's believed about 30 people self evacuated prior to fire crews arriving, the MFB says.
Aerial appliances are tackling the fire from above and are trying to contain it, an MFB spokeswoman said.
The MFB has been unable to confirm what kind of factory is on fire at this stage.
The cause is yet to be established and fire investigators are on scene.