Firefighters throughout the county went to the scene at the former Tauraso Medical Clinic at 7051 Poole Jones Road, and two suffered minor injuries, the News-Post reported.
The house, which is on the historic registry, dates to the 1760s and sits on 14 acres of land. It was gutted by the fire, which broke out at about 8:15 a.m.
David Houck told NBC Washington's Chris Gordon he saw fire and smoke and ran across the street with his camera to take pictures.
As smoke continued to rise from the gutted stone house, a woman who grew up in the area remembered what it was like when she was invited inside as a young girl. Debbie Stitely said it was the most elegant home she had ever been in as a young girl. Seeing smoke rising from the stone mansion was sad.
The house was owned by Dr. Nicola Tauraso who operated a health clinic on the property until closing it and moving away, Gordon reported.
Before opening the Tauraso Medical Clinic, Tauraso opened the Gotach Center for Holistic Medicine in the 1980s, but neighbors opposed rezoning to allow a holistic health center, the News-Post reported.
Paul Beckelman, one of the managers of the property, told Gordon they were planning to turn it into a rehabilitation center for returning war vets. Now their plans are uncertain since the house was to be used as the administrative offices.
Tauraso also owned the restaurant Tauraso's from 1986 until 2006, the News-Post reported.
He has written books on child development, milk, caretakers and stress. He has also authored books on Russia and spiritual philosophy.
Tauraso practiced in Panama from 2006 to 2008.
The cause of the fire is under investigation.