The blaze was reported around 12:10 p.m. at a home in the 700 block of Moraga Road in Lafayette.
Fire crews were able to knock down the blaze in about 30 minutes. An ambulance was at the scene as of 12:45 p.m., but it was unknown how many residents were injured, according to the dispatcher.
As of 12:45 p.m., crews remained at the scene attempting to salvage parts of the home, according to the fire district.
Motorists in the area were advised to expect delays on Moraga Road.