Four people have died in a mid-air collision between a helicopter and a two-seater aircraft, crash scene investigators have said.
A spokesperson for the airstrip said, "Wycombe Air Park can confirm that at 12 pm (local time) today we were informed of an incident north-west of Aylesbury involving two aircraft from Wycombe Air Park".
The UKs Air Accidents Investigation Branch has also sent a team to probe the crash.
Police said officers and members of other emergency services including the fire and ambulance services attended the scene.
"Disruption to road network around Waddesdon likely for the rest of the day".
Superintendent Rebecca Mears of Thames Valley said on Friday evening the aircraft were carrying two people each.
A spokesman for Wycombe Air Park has confirmed both aircraft came from there.
A statement on Twitter read: "Firefighters now assisting other emergency services at scene of air accident near Waddesdon".
Waddesdon Manor, on the Rothschild family-owned estate near the Buckinghamshire crash site, described the latest incident as a "tragedy" and added it "did not happen at the manor nor have there been any casualties at Waddesdon Manor".
A nearby military base, RAF Halton, also said no military aircraft were involved.
Wycombe Air Park is also known as Booker Airfield and sits around 20 miles away from the site of the crash.
Buckinghamshire Fire and Rescue Service confirmed they were at the scene where the aircraft, which is believed to include a light aircraft, crashed, reportedly at a low altitude, near Waddesdon Manor, Aylesbury.
Roger Nock, a pilot, tweeted: "Was flying near Aylesbury earlier".