Stansted Airport has cancelled all departing flights until midnight on Friday evening after an electrical fault caused a passenger shuttle bus to catch fire.
Heavy amounts of thick black smoke affected "much of the front of the terminal building", Essex Fire service said, resulting in an evacuation.
No injuries are reported to have occurred.
#ADVISORY All departing flights have now been cancelled and passengers are politely asked to leave the Airport. We apologise for the inconvenience and advise you to re-book your flight with the airline.— London Stansted Airport (@STN_Airport) March 30, 2018
The bus, which was positioned outside the terminal entrance, was well alight when firefighters appeared on the scene and was completely extinguished by 5.02pm.
Several passengers took to social media to express disappointment at how the evacuation was handled.
Taylor Fulton-Ward, 18, from Hertfordshire, who was flying to Dublin with her family for the Easter weekend, said people were "pushing and panicking" after certain doors were not open to allow people to leave.
She said: "We arrived at the airport and after a lot of waiting we got through security and staff told us all flights were running but delayed.
"After an hour, our flight disappeared from the board with no communication. We went back through to check in to try and re-book the flight but the crowds were crazy.
"Announcements were telling us to leave the building, but the doors were not open - so people began pushing and panicking.
"The biggest problem was not being able to get out the doors and a lack of communication."
A spokesman for the airport said some exits were cordoned off to protect passengers from the burning bus, which was very close to some of the doors, but staff were doing all they could to guide passengers to alternative exits.
Some passengers were given the option of having their luggage mailed to their home address if they needed to leave the airport quickly.
The airport have said it will be operating a normal schedule as of Saturday morning.