A spokesperson for Thames Valley Police said officers were currently at the scene of an air accident near Waddesdon.
"The force is coordinating the response to the incident which was reported at 12.06pm today (17/11).
"The Air Accidents Investigation Branch has been informed and staff are en route to the scene. Fire and ambulance services are also in attendance and preservation of life is first priority.
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"In consequence of this incident it is expected that there will be some disruption to the road network around Waddesdon for the rest of the day," the spokesman said.
The fire service has sent a total of seven crews to the incident. Firefighters from Aylesbury and Haddenham are being supported by colleagues from Oxfordshire and Berkshire.
A spokesman for the Air Accidents Investigation Branch said: "The Air Accidents Investigation Branch is sending a team to investigate a mid-air collision involving an aircraft and a helicopter near Aylesbury."
The Press Association is reporting that both aircraft came from Wycombe Air Park, near High Wycombe.
Both aircraft involved in today's mid-air collision near Waddesdon are understood to have come from Wycombe Air Park, according to the Press Association.
It quotes a spokesman for the airstrip as saying: "Wycombe Air Park can confirm that at 12 o'clock local today we were informed of an incident north-west of Aylesbury involving two aircraft from Wycombe Air Park."
However, a spokesman refused to confirm the report when approached by The Bucks Herald and issued the following statement: "We were informed of an incident at 12.00 in the North West Aylesbury area involving two aircrafts.
"The emergency services are at the scene and the Air Accident Investigation Board have been informed and dispatched a field investigation team."
Transport for Bucks said it was assessing the impact on local roads. In a tweet, TFB said: "A41 is NOT closed, #Aylesbury #Waddesdon. We are investigating any impact on local roads now, more info as we have it."