The cause of the blaze is still under investigation, Belmont-San Carlos Fire Marshal Jim Palisi said.
The fire was reported at about 3:45 p.m. at 641 Waltermire St. Firefighters arrived to find the home's detached garage consumed in flames.
The fire, which is believed to have started in the garage, also extended to the main property, located about three feet from the garage, according to Palisi. It was extinguished within 15 minutes.
Palisi said no one was home at the time of the fire, but one of the family's two dogs was killed in the fire. A garage door was open and the other dog was found outside the garage.
Total damage to the home has been estimated at $180,000.