More than 300 others were injured in the fire that engulfed the Hindu temple complex in Kerala state, where crowds had gathered during the night for a festival that boasted the fireworks show.
A team of specialist doctors was being deployed from New Delhi to the disaster site amid reports of horrific burns suffered by those caught in the blaze at the Puttingal Devi temple.
The navy and air force were also sending helicopters to evacuate the most critically injured, federal health minister J.P Nadda said.
“At least 86 people have died and more than 300 people are injured, who have been taken to the hospitals in Thiruvananthapuram and Kollam,” referring to the state and district capitals.
Firefighters and police battled through the night at the temple in the coastal town of Paravur to douse the fire and rescue those trapped in the gutted temple complex.
Television footage showed a series of large explosions and fireworks erupting as plumes of smoke filled the night air after about 3am (2130 GMT Saturday). Concrete rubble and charred debris was strewn throughout the complex at daybreak, while police examined large unexploded bundles of fireworks.
“Now the situation is under control… the police are on the spot,” Kerala Home Minister Ramesh Chennithala
Kerala Chief Minister Oommen Chandy said temple officials had gone ahead with the fireworks display despite being denied permission because of safety concerns.
“That is correct. District collector of Kollam (was) denied sanction for this fireworks (display),” he said when asked whether permission had been given.
The Kerala government ordered an inquiry into the cause of the disaster. A local lawmaker said it occurred after one firework landed on a building that was storing the rest of the pyrotechnic material.
“It has happened after 75 percent of the fireworks were (already) burst. It was actually fortunate, otherwise the casualties would have been much, much, much more,” N.K. Premachandran, state MP for Kollam district.
The chief doctor at Thiruvananthapuram Medical College said some of those pouring into the hospital had suffered serious injuries “and many would require amputation” of limbs.
“Many have sustained burns of over 50 percent and the condition of some of them is quite serious,” D. Mohandas told the Hindu newspaper.
Prime Minister Narendra Modi said he was flying to the scene and announced 200,000 rupees ($3,005) in compensation for the families of those killed and 50,000 rupees for those injured.
“Fire at temple in Kollam is heart-rending & shocking beyond words. My thoughts are with families of the deceased & prayers with the injured,” Modi tweeted.
“Arranging for immediate shifting of those critically injured via helicopter.”
Navy spokesman D.K Sharma said the helicopters would transport the injured to Thiruvananthapuram and also to the city of Kochi where the navy operates a hospital, with some of the injured currently being treated at small local medical centres.
Fires and stampedes are not uncommon at temples and during religious occasions, often because of poor security arrangements and lax safety standards.
Several thousand people had gathered at the temple for the fireworks show which is held every year at the temple, an official said.
The fire comes as Kerala — governed by the Congress party, which is in opposition at national level — heads to the polls in one of five state elections being held in India this month and next.