The blaze broke out just before 5 p.m. near Nielsen and Marks in Southwest Fresno.
The nearly 12-thousand square foot building has been abandoned for years.
Fire crews responded after someone in the area spotted smoke.
When firefighters arrived on scene flames were already shooting out of the roof.
A man who works at a nearby lumber yard described to action news just how quickly the fire spread.
"You could see the embers starting to pop up on the roof, and then before you knew it, the whole thing just flashed. And then, they'd put it out and it would start flashing again. It happened about 6 or 7 times," witness Leo Mize said.
There's no word yet on how the fire started.
However, fire officials say there have been several break-ins within the area, which makes it "suspicious".
Damage is estimated at $100 thousand.
