More than 60 Firefighters are tackling a blaze in Essex involving 160,000 litres of cooking oil.
They were alerted to the fire at a storage yard in Little Warley, near Brentwood, at 5.15 this morning.
Assistant divisional officer Leigh Corke said 65 firefighters were dealing with the incident involving 160,000 litres of cooking oil, 30,000 tonnes of paper and 30,000 litres of diesel.
Utility companies and the Environment Agency have been called in by the fire service.
A fire service spokesman said: "Once the fire is out, a joint police and fire service investigation will be carried out to establish the cause."
Fifteen appliances are now dealing with the blaze, with fire crews from London drafted in to provide support.
Incident commander, divisional officer Mark Samuels, said he expected the flames to be extinguished by 11am.