Police said the fire broke out due to friction late this afternoon when the workers were sorting the "Karunthiri" (sulphur mixed wicks) and gutted the shed.
Two fire service units brought the fire under control within one hour.
Revenue Divisional officer Kuppusamy ordered evacuation of workers working in the factory as well as nearby units.
The condition of two women and a man was stated to be serious, police said, adding, the others suffered minor injuries.