A CFA spokeswoman said the fire started in a guesthouse extension on a house before spreading into the roof and through to the main part of the home.

But the spokeswoman said some areas of the house were not directly affected by fire, so some items of importance were able to be saved.

A firefighter sustained a minor injury when some debris fell on him, but was able to continue battling the blaze.

The CFA spokeswoman said the fire was a complex one to fight, and it required many trucks on scene to ensure an adequate supply of water.

UPDATE 10.50am: Firefighters remain at the scene of a destructive blaze that has seriously damaged a historic homestead at Kyneton.

The property, owned by TV personality Tonia Todman, dates back 160 years.

Some buildings had been converted into accommodation, while Ms Todman also ran classes from the property.

UPDATE 8.30am: Firefighters at the scene of a fire at an old farmhouse in Kyneton are waiting on ladder support to arrive from Bendigo to fully extinguish the blaze, as the roof of the building has collapsed.

Sixteen CFA appliances are currently on scene at the property on Donnelly Road.

Paramedics have also attended, but no emergency care has been needed.

UPDATE 7.35am: Firefighters have brought the fire under control.

EARLIER: Firefighters are battling a blaze at a historic farmhouse in Kyneton.

The fire at the property Highbank, owned by television personality Tonia Todman, was reported at 6.46am Monday.

The bluestone building on Donnelly Road is fully ablaze and is not yet under control.

The CFA says no one is trapped, nor has anyone been injured.

Ms Todman offered accommodation and classes in cooking, craft, interior design and gardening at the property.

More to come.