The toll in the January 2 fireworks factory blast at nearby Alandur rose to two on Sunday with one more succumbing to injuries in hospital, police said.
The man died at the Thanjavur government hospital after he failed to respond to the treatment being given to him, they said.
The blast killed a worker and left two others seriously injured.
The victims were packing chemicals when the blast, caused by friction, ripped through the godown of the factory.
Police had said the workers had not made proper arrangements before starting work. They had strewn the explosive chemicals all around and were surrounded by the finished and unfinished fireworks items.