Merced firefighters battled a blaze about 1 p.m. Friday at a home in the 1300 block of Eighth Street, authorities reported.
Two children and one woman were safely evacuated. No injuries were reported.
Initally, three Merced Fire Department engines were dispatched to the home. But firefighters were forced to call for additional help to stop the fire from spreading to nearby homes.
The fire did reach the attic of a second house and damaged two sheds.
A total of 26 firefighters were able to contain the fire in about an hour. Firefighters had to cut holes in the roof of the home to clear the smoke.
Merced Fire Chief Michael Wilkinson said that although the investigation was still preliminary, it was most likely that the house, about 1,100 square feet, would be a total loss.
Wilkinson said contents from the second home and the sheds probably be salvaged. He said it was still too early to estimate the amount of losses.
The street was closed for hours after the fire was controlled, but the clouds of remaining black smoke drew neighbors out to watch firefighters work.
The incident commander, Battalion Chief Don Roe, said it was not clear where in the house the fire started.
The cause of the fire remains under investigation.