"They have gone, the roofs have just caved in," she told AAP.
"I can see the flames spilling out of them while I'm talking."
Authorities have blocked off all surrounding streets, including the Bruce Highway, and the shop owner says shoppers have been stopped from saving their cars from the blaze.
"No cars are on fire but it's just too dangerous for them to retrieve them," she said.
"It's just too hot.
"All these people are lined up watching their cars."
Chemicals stored at the Autobarn and Clark Rubber stores are a concern for emergency crews.
"It's the toxic smoke they're worried about," the shop owner said.
Police could not confirm whether any arrests had been made in relation to the fire.
-AAP
