Firies injured battling Sydney fire

Two firefighters have been injured battling a fierce blaze that has engulfed a car wrecking yard in western Sydney.

Fire and Rescue NSW (FRNSW) said 160 firefighters were currently at the yard on Woodpark Road, Smithfield, to battle the blaze that broke out about 8.30am on Saturday.

FRNSW Superintendent Paul Johnstone said the fire had spread to an adjoining furniture factory, but that firefighters had prevented it spreading to a third premises.

He said two firefighters had so far been injured in the operation, one with a deep cut to his hand, the other suffering from heat exhaustion.

"We have contained the fire to the furniture factory and the auto wreckers," Supt Johnstone told AAP.

He said people had been evacuated from surrounding factories, and that the operation would continue throughout Saturday.

On Twitter, FRNSW posted pictures of a compressed air foam system it was using in an attempt to extinguish the large fire.

NSW police say several roads in the area have been closed to traffic, and that diversions are in place.

The Cumberland Highway is closed in both directions at Smithfield between Bruce Street and Stuart Street.