More than 200 firefighters have battled through the night to contain a massive inferno that tore through a waste-facility factory at North St Marys.
Fire authorities say is one of the largest seen in western Sydney in years.
The blaze erupted just before 11pm, when a fireball shot up to 150 metres into the sky above the Kurrajong Road site.
A large chemical tank exploded, launching into the air and sending fist-sized chunks of concrete raining down on dozens of Fire and Rescue NSW (FRNSW) crews fighting to gain control.
More than 50 fire units attended the scene, attacking the flames from all angles and establishing defensive lines through holes blasted into neighbouring buildings.
Two firefighters suffered minor hand injuries during the height of the emergency.
Crews from across Greater Sydney, including five aerial platforms, worked to douse the flames from above.
Hazardous materials teams remain on site this morning managing chemicals involved in the fire.
The Environment Protection Authority, NSW Police and NSW Ambulance are also in attendance.
The cause of the blaze is still unknown, and authorities expect the smouldering structure to burn for much of the day.
Residents have been urged to avoid the area and keep windows, doors and vents closed to protect against potentially harmful smoke.
