Mettur Deputy Superintendent of Police Gopal said that five persons were killed in the mishap that occurred at Parakallur, 42 km from here.
The five injured have been rushed to hospitals here and nearby Mettur.
The explosion was so powerful that the entire godown was razed to the ground, he said.
Thirtynine persons were killed on September 5 in a devastating blaze at a fireworks manufacturing unit near Sivakasi, a hub for crackers in Virudhunagar district.