In short:
A fire at a factory in St Marys has been upgraded to the highest available alarm.
More than 150 firefighters are containing the blaze in Western Sydney, with the fireground still active.
Two firefighters have been treated for heat exhaustion, with nearby residents being evacuated from the area.
The fire, located at the Cleanaway Chemical Waste Recycling Facility in St Marys, is currently contained.
"We've got large quantities of chemicals and gas cylinders that are engulfed in fire and detonating with explosive force.