At least five people, including three women, were killed in a blast at a private fireworks factory in Madurai on Friday, police said.
Citing initial probe, police said chemicals which were being mixed and stuffed caught fire due to friction leading to a series of explosions, severely damaging the structure.
The victims were charred to death.
Several other workers managed to escape to safety, police said, adding fire service units from Virudhunagar and Srivilliputhur were used to put out the blaze.
Condoling the deaths, DMK president MK Stalin demanded that the government ensure safety measures in fireworks factories ahead of Diwali festival.
He sought adequate compensation for the bereaved families.