Over 80 people were killed and several others injured when an explosion took place at the Puttingal Devi temple during a festival at Paravoor in Kollam at around 3 am on Sunday, police said.
As the temple festival was on, fireworks display had commenced at the temple precincts since midnight and hundreds of people had gathered to watch the show.
As the fireworks and pyrotechnics display was coming to a close at 3 am, an explosion is suspected to have occurred at the storeroom 'Kambapuram' filled with crackers and pyrotechnics materials, police said.
Men, women and police officials are among the dead, they said.
Fifty of the injured have been rushed to Trivandrum Medical College in the state capital and five persons died after being brought there.
Nearly 200 people got injured in the mishap and have been admitted to various hospitals in the district and nearby Thiruvananthapuram, police said.
Kerala Chief Minister Oommen Chandy termed as "unprecedented" and "alarming" the situation at the Puttingal Devi temple.
Chandy, who cancelled all his scheduled poll programmes, is on his way to the accident site.
"Rescue operation at the mishap spot is over...The next main focus of the government is to provide best treatment to the injured," he told PTI.
Asked about the death toll, the Chief Minister said the number would go up as reports are pouring in from different hospitals, where the injured have been admitted.
"This is an unprecedented and alarming situation," Chandy said.
The government would extend treatment facilities to the injured persons in the hospitals preferred by their relatives, he said.
The State Chief Secretary has been asked to write a letter to the Election Commission for necessary sanction to exclude the treatment facilities to the injured from the ambit of the Election Code of Conduct, he said.
State Health Minister VS Sivakumar said directives have been issued to hospital authorities to make necessary arrangements for the injured.
State Home Minister Ramesh Chennithala said Director General of Police (DGP) Senkumar is monitoring the rescue operations.
"A comprehensive probe will be conducted into the incident. Adequate compensation would be given to the victims of the accident after consulting with the Election Commission," Chennithala said.
Local media reports quoting Kollam district authorities say the temple authorities ignored warnings issued against holding a huge firework in the area vulnerable to such accident.
District Collector Shinamol, who visited the spot, said evacuation and rescue operations were going on full-swing. People trapped in the concrete structure, which was completely destroyed in the mishap, were taken out, police said.
Eye witnesses told television channels that the accident took place at 3.30 am.
The sound of the explosion in the store-room was heard in around two-km radius of the temple, they said.
(With inputs from PTI)