A man who died in a motocross crash at Besthorpe, near Attleborough, has been named locally as Mark Davis, aged 51.
Police were called to Silver Street shortly after 3.30pm on Saturday after reports a man riding a Honda 250cc motocross bike had sustained serious head, neck and chest injuries.
The East of England Ambulance Service and the East Anglian Air Ambulance attended but he was pronounced dead at the scene.
He is believed to have lived near Diss.
Manager of Besthorpe Moto X and Quad Tracks, Mark Brown, said it was the first time Mr Davis had been on a motocross bike in 25 years, and his death was the result of a freak accident, and involved no-one else.
He said: “We have our own medical staff and an emergency medical technician on site. He was on the scene within a matter of seconds and safety marshals were backing him up.”
Mr Brown said he and staff had been left shaken and upset by the incident. The motocross community was still mourning the loss of Tom Pattison, who died at the Blaxhall Circuit in Suffolk last month, aged in his 20s.
Mr Brown said the Health and Safety Executive, who initially investigated, cleared the circuit of any responsibilty.
He said: “It (motocross) is a very dangerous sport - always has been, and always will be. That’s the sport it is and that’s why people enjoy it.
“But it is very rare to get two deaths so close to each other. You never expect to go through a death. I put a lot of my spare time into this track for people to have fun on, not to die. It has hit me pretty hard.”
Mr Brown closed the track on Sunday as a mark of respect to the family. It will reopen again at the weekend as normal.
A spokesperson for Norfolk Constabulary said Breckland Council’s environmental health department was made aware and attended the scene and is now leading the investigation.
Motocross is an off-road motorcycle racing sport, involving jumps, hills and turns.