A MASSIVE fire has engulfed a factory complex in Sydney's west, with 80 firefighters working to bring the blaze under control.

The multiple occupancy site at Seven Hills is home to a number of businesses, including the Singer Sewing Machine headquarters.

It's understood the fire has consumed a number of buildings.

A New South Wales Fire and Rescue spokesperson said 25 trucks were at the scene and some 80 firefighters are battling the inferno.

Large plumes of black smoke can be seen rising from the complex, as well as flames through broken windows in a number of the buildings in the complex.

Reports indicate that Prospect Highway in Seven Hills, which is near the site, has been shut down in both directions.

Authorities said all individuals had been accounted for and there are no reported injuries at this stage.

People are advised to avoid the area until the situation is contained.

Temperatures have soared across the state over the past two days, with fire crews on high alert.

More to come.