Fresno fire investigators are trying to figure out what started a blaze that tore through a business near the Fresno Yosemite International Airport.

Fresno Firefighters responded to the area of Sunnyside and Harvard Avenues around 2:30 p.m. White smoke could be seen billowing above GS Auto Shop. 

Firefighters said when they arrived, they found a heavy fire and smoke inside. The fire department said the smoke also damaged a machinery business next door. 

Firefighters said they had some challenges including not knowing what was stored inside the building, and the material of the structure.