Firefighters have spent the night tackling a major blaze at Scalesceugh Hall, on the A6 at Carleton near Carlisle.
Fire crews were called just before 11pm.
The listed building was well-alight on arrival.
Multiple firefighters from across the north of the county, including Brampton, Carlisle, Penrith, Lazonby and Wigton were called to tackle a the blaze.
The incident used a lot of resources including an aerial ladder platform, water bowser (which carries 7,000 litres), joint incident command unit, unimog (multi-purpose vehicle) and around seven appliances.
Stuart Hook, incident commander, said: “Initially we mobilised two fire engines from Carlisle, but as we arrived we saw that the fire was going through the roof.
“We saw it was a well-developed fire on arrival. At that point we had people missing and our priority was search and rescue.
“It soon became apparent that everyone was accounted for, and by that point we had got about eight appliances out.
“The main part of the listed building is understood to have been destroyed, but the efforts of firefighters prevented the flames spreading to any of the other buildings on site.
“Our initial problem was water. We’ve had to use vehicles to ferry water – we had a water relay set up., and we had to use our water bowser which carries 7,000 litres and our wildfire unit which carries about 4,000 litres.”
The fire was brought under control at around 6am however crews remain on the scene to extinguish any hot spots.
Everyone has been accounted for and there were no casualties.
Owners of Scalesceugh Hall & Villas, Bruno and Anita Herdeiro said in a statement: “It is with deep sadness that we can confirm the main building of Scalesceugh Hall was extensively damaged by fire last night.
“Thankfully, nobody was hurt, and all the residents of Scalesceugh Villas were evacuated safely as a precaution.
“The villas were not touched by the fire, and our Wellness Centre, currently being constructed, was also undamaged.
“We owe an enormous debt of gratitude to firefighters who attended from across the area for their tireless efforts to bring the blaze under control and stop it spreading any further.
“We have put our hearts and souls, time, love and much money into restoring the Edwardian mansion that brought us to this beautiful corner of Cumbria.
“This is a very difficult day for us. We are devastated by what has happened.
“Nevertheless, we remain committed to our dream, to provide a stunning place to live at Scalesceugh. This setback, though devastating, will not deter us from carrying on.
“Thank you to everyone for your concern and support. We will be releasing more statements in time, on our website, on social media and in the local media.”