The toll in the cracker unit fire at Kalayarkurichi near here has risen to seven, officials said on Saturday.
The condition of five injured is stated to be serious, they said.
Officials said the fire that swept through parts of the factory on Friday was caused due to alleged mishandling of chemicals and all the deceased were women workers.
The officials said the cracker unit was owned by one Kanakaprabhu who was making a fancy variety of crackers.
About 200 workers were employed in the factory.
Most of the workers escaped as they were having their lunch, away from the site where the fire broke out, officials added.
