Over 50 firefighters have tackled a blaze at a house in St Austell that threatened to engulf an entire terrace.
Crews were called to the property in Holmbush Road at around 3am.
The terraced house that caught fire was unoccupied at the time, but there were fears the blaze would spread to the surrounding six properties so all residents were evacuated.
Eight appliances with over 55 firefighters from St Austell, Fowey, Mevagissey, St Dennis, Lostwithiel, Bodmin, Truro, Launceston and Falmouth attended the incident.
Police, ambulance, Transco and Western Power are also at the scene.
One neighbour described waking up hearing her dog barking at a smoke alarm before smelling smoke and seeing flames "leaping" from the house.
The fire is now out but residents are not being allowed back to their homes yet while safety checks are carried out and investigations into the cause of the blaze take place.
A spokesman for Devon and Cornwall Police said: "Local residents are not yet able to return to their homes. Some have gone to stay with relatives and the local Tesco supermarket opened to provide shelter. Everybody is accounted for and the fire is not being treated as suspicious."
Steve Halstead, the incident commander from Cornwall Fire and Rescue, said his crews fought "very, very hard" to stop the blaze spreading through the roofs and he regarded the response as a "great success."
The A390 Holmbush Road is currently closed in both directions between Mount Charles Roundabout and Daniels Lane, but is expected to reopen before 10am.