Four people have died in a mid-air collision between a helicopter and a two-seater aircraft, crash scene investigators have said.
Both of the aircraft are understood to have come from Wycombe Air Park and collided near the village of Waddesdon, in Buckinghamshire, shortly after midday.
Superintendent Rebecca Mears of Thames Valley said on Friday evening the aircraft were carrying two people each.
She said she could not give any details of the identity or the genders of the victims at this stage and her “first priority” at this stage was the next of kin.
The two aircraft came down close to the famous Waddesdon Estate, the former country seat of the Rothschild banking dynasty.
The plane involved was a Cessna 152, built in 1982 and owned by Airways Aero Associations which is based at the Wycombe Air Park.
It had flown almost 14,000 hours as of May and had previously suffered substantial damage to its landing gear, propeller and engine following a crash at a Cornish airfield in 1993.
An archived report by the Air Accidents Investigation Branch (AAIB) shows the pilot admitted the accident was caused by his “misjudgement and lack of experience”.
Ms Mears said: “Our priorities today remain with investigating the next of kin, finding out who they are, informing them and supporting them with specialist officers as we progress the investigation here on site.
“We anticipate being here until about Monday morning, potentially longer, we do not rush these things, it’s really important we do a meticulous investigation”.
Police said it was “too early to tell” what might have caused the crash.
A Notice to Airmen was previously issued to warn pilots the Wycombe Air Park’s air traffic control services would be closed during three 30-minute periods on selected days between November 7-30 due to a “staff shortage”.
The crash occurred around half an hour after the latest closure was due to end.