British Stansted Airport in Essex county was partially evacuated on Friday afternoon after a fire on a car outside the building sent flames and plumes of smoke into the air.
At least one fire engine was seen rushing to the scene and police diverting traffic away from the terminal, the airport tweeted.
Flights were delayed as airport officials said they were urgently investigating the fire that broke out on the car park shuttle bus.
The airport tweeted at 16:40 BST that due to a fire on a car park shuttle bus, the terminal forecourt and parts of the terminal building were being evacuated.
"We are investigating this as a matter of urgency and will provide an update shortly," it said.
Essex Fire Service said four fire crews had been sent to the scene.
Passengers also reported that flights had been delayed.
Some of them complained at being stuck outside the terminal building while others were dismayed by what they said was the lack of an action plan.
At 17:12 BST, the airport tweeted: "The fire has since been put out and we're working on returning to normal operations. More updates to follow."