The Power Fire is burning along Powerhouse Road near the Kirckhoff Reservoir.
So far it has charred about 115 acres and is 10% contained. CAL FIRE says that four firefighters were hospitalized with heat-related injuries.
The fire is spreading to the southeast and officials say a "minimal number" of structures are threatened.
An evacuation warning is in effect for Powerhouse Road and all side roads from 0.25 miles north of Wish I Ah Rd to the Fresno / Madera County Line. The north, east, and west boundaries are the San Joaquin River.
Stay with ABC30 for the latest details on this developing story.