Investigators say an electrical fire started in the attic of the house on Northdale Avenue near First Street around 2 p.m. Sunday afternoon.
Crews saw smoke pouring from the vents when they arrived.
Everyone made it out safely but a battalion chief says firefighters faced an extra hazard because the family had collected a lot of belongings.
"We had hoarder situations inside the home as well as throughout the backyard, so when you have that type of fire load, it's very dangerous for firefighters," Fresno Fire Battalion Chief Chuck Tobias said.
The exact amount of damage is not yet known, but fire officials are estimating they saved at least $35 thousand worth of the property.