A vintage aircraft has crashed at an air show in Bedfordshire on Sunday.
The condition of the pilot, a man in his 40s, was not immediately known, police said.
The "serious" crash happened at Old Warden Aerodrome, near Biggleswade, Bedfordshire, which is home to the Shuttleworth Collection of vintage aircraft, as 600 people attended a military pageant show.
Police said they worked alongside the fire and rescue service, East of England Ambulance Service and the aerodrome's own fire service to help the pilot.
The collection confirmed in a statement on its website that an aircraft had experienced difficulties and crashed.
"Emergency services and the air ambulance were called to the scene and one casualty airlifted to hospital.
"We are not releasing details of the person's identity or the nature of the injuries incurred.
"Today's planned air show has been cancelled to allow accident investigators to assess the scene.
"We would like to thank both on-site and external emergency crews for their prompt reaction."
A spokesman for the Air Accidents Investigation Branch (AAIB) said that the aircraft involved was a DH 53 vintage aircraft.
"A team of inspectors have been despatched to the site, to start an investigation which will determine the circumstances behind the accident," he added.