Firefighters are tackling a fire in a range of outbuildings in Johns Way, Buckles Lane, South Ockendon.
A 1,000 litre propane tank is believed to be involved in the fire along with other cylinders.
It has also been reported that caravans are also alight.
There are no reports of any injuries.
Ten fire crews, several police cars plus the helicopter are in attendance.
Crews are being hampered at the scene by members of the public as well as a lack of a good water supply.
Police have closed a number of roads to give the fire service as much room as possible.
YT spoke to one of the residents of Buckles Lane, John Biddall.
He said: “I am in Croydon at a show but my wife had just tried to return to the site but cannot get near.”
Local councillor Lynn Carr was on a ward walk when she heard the explosion.
She said: ” I was in North Road when I could see smoke but a resident lived much closer and felt her house shake.
“I just hope nobody has been injured.”