More than 70 firefighters are tackling a fire at Norwich International Airport.
Eight fire crews are fighting the blaze that broke out in a hanger containing two aircraft filled with more than 5,000 litres of aviation fuel.
The hangar is used by KLM Engineering and Air Livery and is located near a number of shops and other airport hangars.
Fire service incident commander Greg Preston said that neither aircraft had been damaged, but added that assess the fire was proving "very difficult".
Mr Preston said: "We have currently got crews working at height using our aerial platform. We are removing the roof covering to extinguish the fire and to ascertain the extent of the fire spread.
"It's very difficult access given the height of the building. It's really difficult to access from the inside. It's going to be a protracted incident. As we strip away the roof we will be able to see the extent of the fire."
There are are no reports of any casualties and the fire is not being treated as suspicious.
A spokesman for Norwich International Airport said: "The fire is being controlled by the fire services, and is taking place in an Air Livery hangar. The airport and services are not affected."