The 280 metre-long building on the Yarra Industrial Estate, off Station Road, Ecclesfield, is thought to have been struck by lightning.
A South Yorkshire Fire and Rescue spokesman said the fire has now been extinguished, and some explosions would have been heard towards the end of the incident at around 10am.
He said: “We reassure people that this was an expected part of firefighting operations which helped bring the incident to a close.”
Fire crews were called to the site just after 4am on Saturday, July 4.
At the height of the fire, seven fire appliances and an aerial platform were in attendance.
By 10.30am, fire crews were cooling off and damping down at the scene.
An investigation into the cause is under way and will continue over the weekend.
South Yorkshire Fire and Rescue confirmed a number of properties across the region were hit in last night’s massive thunderstorm, which began at about 3am.
There are also reports of flooding in some areas.
Local residents are advised to keep their windows shut.