Vitafoam, which produces foam for sponges that are inserted into mattresses, exploded into flames at about 8am yesterday when the company's premises in Industria, Johannesburg, caught fire.
As the fire raged, a company official braved the flames and entered the building, later emerging with four computer hard drives.
Although none of VitaFoam's 200 workers were injured, nine from neighbouring Nampak Liquid Packaging Company were treated for smoke inhalation at the Garden City and Flora clinics.
Four hours later, huge explosions could be heard as the single-storey 50-metre-long building continued to burn while the flames grew stronger.
Fulton and Commando roads were closed as police and emergency personnel stopped curious onlookers who had gathered to witness the inferno.
"About 200 workers were inside the company when the fire started, but all were evacuated and accounted for," said Johannesburg emergency management services spokesman Percy Morokane.
He said those taken to hospital were in a stable condition.
Morokane could not estimate the extent of the damage, but said it could run into millions of rands.
Later in the day, Vitafoam's general manager Dave Schutte issued a statement assuring customers that their supplies would not be interrupted and that the majority of the workers at the firm were not affected by the incident.
Other companies situated closer to Vitafoam, including Nampak and Elster Kent Metering, also evacuated their premises fearing the fire might spread to their buildings.
lSee also pages 10 and 11.