The massive blaze at the Puttingal temple complex in Paravoor village, Kerala state, has left more than 100 dead and at least 200 others have been hurt, officials say.
Chief minister for Kerala, Oommen Chandy, said a spark from an unauthorised fireworks show ignited a seperate collection of fireworks.
Officials report thousands were packed into the site when a large explosion occured at around 3am, before many devotees became trapped as the fire quickly spread.
The temple was staging a competitive fireworks display during the end of a week-long festival honouring the goddess, Bhadrakali.
Speaking to Premier Christian Radio, Dr Sam Paul from the All India Christian Council said temples in India can be hectic places and may lack clear security plans.
He said: "In India, we are not used to queuing up anywhere. We just rush. So in the temples, they want to see the deity, they rush in big numbers and arrangements are not so clear.
"We are very concerned about this incident. It's horrendous. It's very sad. We ask the UK to pray this would not be repeated."
Local resident, Krishna Das said: "It was complete chaos. People were screaming in the dark. Ambulance sirens went off, and in the darkness no one knew how to find their way out of the complex."