The Fresno Fire Department says it happened around 3:15 am at a home near 5th and Woodward.
They say the house was occupied by the homeless but no one was inside when they searched.
The fire started in the attic and then spread to the rest of the house.
A wall fell on one of the firefighters during the firefight. He was taken to the hospital with minor injuries and is expected to make a full recovery.
Firefighters were also able to save a puppy from the flames. It has since been taken to CCSPCA.