More than 50 firefighters are trying to get the fire, at a factory on Fillo Drive in Somerton, under control.

All roads connected to Fillo Drive are closed and authorities have advised people there is significant smoke from the fire affecting Broadmeadows, Campbellfield, Coolaroo, Craigieburn, Dallas, Epping, Greenvale, Lalor, Meadow Heights, Roxburgh Park, Somerton, Thomastown, Wollert.

The Metropolitan Fire Brigade has issued a warning to those living nearby.

“Anyone located in suburbs adjoining Somerton should take shelter indoors immediately,” the warning reads. “Close all exterior doors, windows and vents and ensure that heating and cooling systems are turned off.

“Fillo Drive and adjoining roads are currently closed and people are advised to avoid the area.”

Thick black smoke can be seen billowing into the sky above the factory. The fire is understood to have begun at 12.30pm.

Part of the factory’s wall collapsed in the inferno and the cause of the blaze is not yet known.

No injuries have been reported.

What you should do if you are affected:

- Close all windows and doors and turn off your heating and cooling systems.

- Bring your pets indoors.

- Keep the roads clear so emergency services can respond.