A five-year-old girl has died after being struck by a slow moving vehicle in a field at the Lanlivery Vintage Rally.
The tragic incident occurred at 11.40am yesterday as the child attended the event near Lostwithiel with her foster parents.
She was treated by paramedics less than a minute after being struck as they were present at the show on a display stand within 100m of the location.
The little girl, from Devon, was airlifted to Derriford Hospital where she later died.
A spokesman for Devon and Cornwall Police said: "CPR was being undertaken at the point the air ambulance lifted from the scene.
"Local police attended, later being joined by officers from the Bodmin Serious Collisions Investigation Unit who will conduct a full investigation into the incident.
"The child was with her foster parents who live in Devon, her details are not being released at this time until interested parties are all aware."
They said the two day show would continue today as planned, with the grieving family's agreement.
Organiser Diane Williams said the girl was hit by an "old-fashioned" four wheel drive vehicle that had been reversing slowly in the field.
She said: "It was a tragic accident. It was not the driver's fault but he feels awful as you can imagine.
"The girl's family attended a church service at the site today which was very moving. We have never had an accident before in 28 years. It is appalling."
The Lanlivery Vintage Rally, Steam Fair and Country Fair is held on the second weekend of September each year and raises money for local charities, this year including the Cornwall Air Ambulance.
The show posted a message on their Facebook site yesterday evening saying: "A tragic accident occurred at the Rally today. The family involved have expressed a wish that the Rally should continue today and tomorrow, particularly as it is raising money for the Air Ambulance which came to help.
"The family and the Rally organisers request that this incident is not talked about on Facebook as it is very upsetting for the family at this sensitive time.
"Great sympathy goes out to the family from the Rally Organisers and the people of Lanlivery."
The Health & Safety Executive were informed of the girl's death but did not attend the scene yesterday.