The accident occurred when the temple chariot came in contact with a high-transmission live wire in Thanjavur district, police said, BBC reported.
Two children were among the dead. Officials said the toll could go up as some of the injured were critical.
A case has been lodged and police have opened an investigation.
Fire and rescue services official Bhanupriya, who uses only one name, told BBC Tamil that a generator which was powering the chariot got stuck on a curve in the road. While adjusting it, the top of the chariot came in contact with the high-voltage wire.
Eyewitnesses said the toll could have been much higher if it had not been for a puddle of water on the road - around 50 devotees walking alongside the chariot had stepped aside mere seconds earlier to avoid it.
RHM/PR