The Campbellfield factory fire was brought under control in 44 minutes.

A factory blaze has sent smoke billowing over Melbourne's north, as firefighters stop the flames from spreading to a chemical storage facility next door.

Six employees of a mechanic's workshop in Campbellfield were safely evacuated on Thursday morning after the Metropolitan Fire Brigade were called to the Malcolm Place factory at 8.52am.

Nearby residents told 3AW radio of hearing an explosion, and smoke is moving in a southerly direction across Melbourne's north.

A statement issued by the MFB at 9.35am confirmed the fire had been brought under control.