By 2pm the fire had been extinguished but firefighters remained at the scene to damp down remaining hot spots using thermal imaging cameras and cut away parts of the roof to make sure the fire was completely extinguished.
London Southend Airport is around 68 kilometers (42 miles) east of the United Kingdom capital.
A spokesperson for Essex Fire Brigade said: "Firefighters have been called to an incident this morning involving an aircraft hangar".
A fire has broken out in a hangar by an airport runway.
Six fire crews are tackling the blaze after it was reported at about 10:40 BST. "London Southend Airport is still open and operating as normal", a fire service spokesperson said.
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'I could see the flames from the terminal - they were not particularly high but it was really thick black smoke'.
"The hangar did not have any aeroplanes inside", said Essex County Fire and Rescue Service in a statement.
A total of eight crews have been sent to the scene from Southend, Rayleigh, Rochford, Shoeburyness, Hawkwell and Chelmsford.
A fire has been put under control after an explosion took place at an aircraft hangar on the north side of London Southend Airport in Essex on Wednesday, fire fighters and rescue staff said here.