An aircraft and a helicopter are believed to have crashed in mid-air over Buckinghamshire.
The Air Accidents Investigation Branch said it is “sending a team to investigate a mid-air collision involving an aircraft and a helicopter near Aylesbury, Buckinghamshire”.
Emergency services were called to the site, near Waddesdon Hall, at 12:06 GMT.
Police said disruption in the area is expected for the rest of the day.
Thames Valley Police, the ambulance service and fire crews from Aylesbury, Haddenham, Oxfordshire and Berkshire are at the scene.
More follows.
BBC