The flames broke out just before 8 on Sunday morning at a house on Sierra Vista and East Montecito.
Fire crews arrived to find that fire coming from the back bedroom of the home.
Crews searched the house and didn't find anyone inside.
Crews were able to control the fire in the room it started in and slowed the spread to the attic.
The cause of this fire is still under investigation but officials say they believe that fire was caused by illegal electrical work in the home.
"The house itself does not look like it's normally occupied, it looks like it might be used for some illegal marijuana growing," Fresno Fire Battalion Chief Bob Camp.
"It is possible that it is completely legal however until they meet with the property owners, go through that process and determine the intent of their growing inside the structure, it will be determined at that point," he added.
Fire and police officials are still investigating.