She is described as a white female, 14 years old with below shoulder-length blonde hair and is approximately five foot eight in height.
The girl, who has links to Bodmin and St Austell, is understood to be wearing white Nike trainers, light blue jeans and a gray hoodie, and a black puffer coat as seen in the photograph police shared.
Police are concerned for her safety and well-being.
Locals have noticed a large police presence, including a helicopter circling the area.