A pilot has died after a plane performing a stunt in an aerial display crashed at CarFest in Oulton Park, Cheshire, event founder Chris Evans has said.
Visitors to the motoring and music festival tweeted photos of smoke rising near the scene of the event and spoke of shock after witnessing the crash.
The festival, which was opened new Top Gear presenter Evans, raises money for BBC Children in Need.
A tearful Evans confirmed the death this afternoon and said the pilot's family had been informed. He said there had been a "tragic accident, the result of which was one of the pilots involved in a synchro display lost his life".
The jet was one of two involved in the display at the motor racing track in Little Budworth - with the other landing safely nearby.
One witness wrote on Twitter: "Feel sick I just witnessed a plane crash at carfest. Literally flew over my head and blew up on a ball of flames in a field."
Others described horrified spectators screaming as a plane nose dived suddenly during a display.
Witness Adam Ignatowicz told the BBC: "I was at the shop. There were two planes flying around. One of them just seemed to do a dive where the car park is. Then there was a bang.
"There were emergency services running through. Air Ambulance is there now. Everyone's questioning what's happening. Everyone realised what had happened. The other plane went straight over to see what was happening."
Evans tweeted soon after the crash, which occurred around 2pm: "I am very sad to announce there has been a serious air incident at CarFest North off site. The emergency services are in attendance."
Other celebrities, including The Great British Bake Off's Paul Hollywood and fellow TV chef and motoring enthusiast James Martin, were also due to attend the event.
Cheshire police said the plane came down in a wooded area near Oulton Park: "Shortly after 2pm we received reports of a plane having crashed in a wooded area near the CarFest North site.
"Officers are currently at the scene working to find out what has happened.
"The incident is in a very early stage and more details will be released when they become available.”
The plane is believed to have been part of the Gnat Display Team based North Weald Airfield and part of the Heritage Aircraft Trust. The unit are billed as the only civilian supersonic jet aerobatic display team in the world.
The Gnat Display Team is owned and operated by Heritage Aircraft Limited, the trading arm of The Heritage Aircraft Trust, a charity registered in England & Wales. It's believed the two planes were ex-Red Arrows jets.
Video posted on Twitter showed the crash aftermath:
While another user posted video of the moments before the crash:
Chester Chronicle journalist Mark Dowling told the Manchester Evening News that there were two aircraft doing a dual display.
"I thought one of them appeared to be a bit low. It was upside down when I saw it go behind some trees, then suddenly there was a huge smoke cloud and flames.
"There was a gasp from the crowd. People are really worried, hoping that the pilot managed to eject.
"It looked like the plane landed in a field about half a mile north of the circuit."
The festival, which opened on Friday and closes tomorrow, was also due to hear performances from the likes of Joss Stone and Primal Scream.
CarFest is described on its Twitter profile as Evans's "dream of the perfect family festival", featuring cars, planes and music. The event is continuing despite the crash.
Evans is a car enthusiast who has just become the new presenter of Top Gear.
He is taking over from Jeremy Clarkson whose contract was not renewed after he punched a member of the show's staff during a fracas. Former Top Gear co-hosts Richard Hammond and James May have now also teamed up with Clarkson for a motoring show on Amazon.