Twelve people injured in the accident are still undergoing treatment in various hospitals in the district.
The owner and manager of the cracker manufacturing unit have been arrested, police said. A case has been registered, against them and an investigation has begun.
A massive fire broke out at around 10.20 pm on Monday after an explosion at the godown of the cracker unit situated in Vetriyur Viragalur village of the Ariyalur district.
According to police, the explosion took place when workers were involved in manufacturing country crackers for local temple festivals.
Fire tenders from Ariyalur and Perambalur districts rushed to the spot immediately and doused the fire after several hours.Ariyalur District Collector J Anne Mary Swarna and District Superintendent of Police (SP) K Feroze Khan Abdullah reached the spot immediately after receiving information about the incident.