Describing the tragedy as "unimaginable", Prime Minister Narendra Modi on Sunday assured Kerala government and its people all help. With more than 40 bodies yet to be identified, he has also offered help for DNA testing.

Officials say 10,000-15,000 people were present at a ground next to the temple in Paravur watching fireworks during a festival to honor Goddess Kali when the fire started a little after 3 am.

A spark during the fireworks ignited a stack of firecrackers stored in a nearby two-storey building and led to an explosion, witnesses have said. The impact brought down the building around which people had gathered. Within minutes, huge flames engulfed the temple.

Chief Minister Oommen Chandy said the temple was not given permission for the "competitive fireworks", a tradition during the week-long festival. The ban came after the district administration took into account a complaint by a woman who lived close to the temple.

Kerala is studded with temples managed by rich and powerful trusts that often flout local regulations. Each year the temples hold fireworks displays, competing to stage the most spectacular ones, with judges who decide the winners.

But at 3 am, as a spark landed on the stockpile of fireworks, the pile went up. Explosions lit up the night sky and then, a huge cloud of white smoke covered area. Successive explosions sent huge chunks of concrete flying as far as a kilometer according to a witness. Some parts of the temple roof caved in.

A police case has been registered against the temple authorities and a judicial probe has been ordered.

The injured have been taken to 10 hospitals in and around Kollam. Those critically injured are being shifted to hospital using choppers. Three naval ships and 10 air force and naval aircraft have joined the rescue efforts.