Firefighters saw black smoke coming out of the middle and north end of the building when they arrived, fire department Deputy Chief Chris Forrester said.
When crews entered the building, they found one of the forklifts had caught fire, he added.
“When we were setting up to enter the building, there were two very loud pops, and my best guess is that those were the tires exploding on the forklift,” Forrester said.
The sprinkler system had turned on and extinguished most of the blaze, according to Forrester.
Any damage inside the building was likely due to smoke or water damage, not flames, he added.