Dozens of passengers were treated for breathing difficulties after a suspected chemical incident at London City Airport.
Two casualties were taken to hospital and 26 people received treatment at the scene, London Ambulance Service said.
A spokesman for London Fire Brigade said three fire engines and a range of specialist appliances were sent to the airport following reports of a "chemical incident". The cause of the incident is not yet known.
Medics specially trained to treat people in hazardous situations are at the scene.
Around 500 members of the public and airport staff were evacuated, and the airport closure has led to travel chaos.
All flights were suspended and several incoming planes from Frankfurt, Amsterdam, Belfast City and Paris were diverted to other airports.