A cordon has been set up by police as firefighters tackle a large blaze involving two caravans and a number of gas cylinders.
Motorists have been warned that it may be possible to see smoke from the A30, but fire crews are working to put out the flames.
Cornwall Fire and Rescue Service received three 999 calls just after 5.15pm, reporting a caravan on fire in North Country near Redruth.
Two crews were sent from Tolvaddon, along with a group manager from Truro Fire Station.
A fire service spokesperson said: "On arrival the first appliance confirmed there were two static caravans well alight, with gas cylinders involved. Police were requested to assist with road closures."
At 5.37pm a 'make pumps three' assistance message was sent following discovery of six cylinders, and a crew from Truro sent to the incident.
With support from police, a 50-metre cordon is now in place, meaning the closure of Radnor Road.
Crews are using a ground monitor to extinguish the fire and are defensive firefighting due to the risk to personnel, said the fire service.
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