At least three people are feared to have died after a plane collided in mid-air with a helicopter in Buckinghamshire.
The crash took place close to the village of Waddesdon, near Aylesbury, about some 40 miles west of London.
Emergency services, including firefighters rushed to the scene, following reports of an incident at 12.06pm, Thames Valley Police said.
Early media reports claimed that as many as three people had been killed by the collision.
South Central Ambulance Service, reported the BBC, that it had sent crews to the scene.
‘We received the call at 12.09pm, for a mid-air collision involving a helicopter and an aircraft in Upper Winchendon, near Aylesbury.
‘We sent a number of resources to the scene, including a Thames Valley air ambulance, two ambulance crews, two ambulance officers and a rapid response vehicle.
‘There have been a number of casualties at the scene, but at this stage this is all we are able to confirm.’
We're aware of a number of casualties following an incident this afternoon in Waddesdon, Aylesbury.
There were a number of road closures following the incident, which have now been lifted.
We will provide further updates when available.
— Thames Valley Police (@ThamesVP) November 17, 2017
An Air Accidents Investigation Branch said it was ‘sending a team to investigate a mid-air collision involving an aircraft and a helicopter near Aylesbury, Buckinghamshire’, but police said the priority was being placed on saving lives.
However, the AAIB confirmed the collision was between a helicopter and plane.
The incident happened at around midday, said Thames Valley Police.
Both aircraft involved in the mid-air collision came from Wycombe Air Park, near High Wycombe, a spokesman said.
Update on mid-air collision between light aircraft and helicopter near Waddesdon:
Thames Valley Police have confirmed that they are aware of a number of casualtieshttps://t.co/itiXfBq3Eu
— Bucks and MK Fire (@Bucksfire) November 17, 2017
Thames Valley Police also tweeted that there had been casualties and said it would provide further updates later.
The airfield is also known as Booker Airfield.
According to its website, it looks after ‘more than 200 aircraft for club members and other airfield users including gliders, rotary wing aircraft and vintage aircraft such as Tiger Moths’.
It also runs flight training courses for trainee pilots.
Casualties were also confirmed by the Bucks and MK Fire service.
A plane has come down at Waddesdon Hill – currently at scene. More to come as we have it pic.twitter.com/ZLl51n6JnP
— Hayley O'Keeffe (@misshoknews) November 17, 2017
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Buckinghamshire Fire and Rescue Service said they currently have seven vehicles responding to the incident, including fire engines as well as urban search and rescue vehicles.
Thames Valley Police are co-ordinating the response to the crash and warned there will be disruption to surrounding roads for the rest of the day.
Thames Valley Air Ambulance are also at the site of the crash, a spokesman said.
Waddesdon is the location of a National Trust property, Waddesdon Manor.
A spokeswoman for the Manor, said the crash had not happened on its grounds.
Waddesdon Manor is managed by the Rothschild Foundation, a family charitable trust, on behalf of the National Trust, who took over ownership in 1957.
The crash is believed to have taken place to the family home of the Rothschild family.
RAF Halton, which is around 10 miles away, said no military aircraft had been involved.
A spokesman said: ‘We can confirm that neither of the aircraft concerned has a connection with either our air force nor the military, and this is as much as we know at this time.’