At least 13 people have been killed in an explosion at a firecracker factory in India's southern state of Kerala, officials say.

The incident took place in Thrissur, where around 40 people were believed to be assembling firecrackers in a cluster of sheds for an upcoming festival. Several others were injured, with five reported to be in critical condition.

This was the second such incident this week. On Sunday, a blast at a firecracker factory in neighbouring Tamil Nadu state left at least 25 dead.

Accidental explosions are a grim routine in India's fireworks industry, recurring with troubling regularity - most visibly around Sivakasi in Tamil Nadu, which produces much of the country's supply.

The explosion in Thrissur on Tuesday around 15:30 local time (10:00 GMT) triggered secondary blasts that slowed rescue efforts. Firecrackers were being made in temporary sheds near paddy fields with poor road access, hampering emergency response.

The force of the blast was felt kilometres away - some residents mistook it for an earthquake - and nearby homes were damaged.

Eyewitnesses described chaotic scenes as locals joined rescue efforts, pulling out the injured and dead. Kerala's Revenue Minister K Rajan confirmed that all fireworks units preparing for the upcoming Thrissur Pooram festival had the necessary permissions.

Officials indicated that food had been prepared for about 40 workers, implying at least that many were inside the shed during the blast. While the municipal chairman attributed the explosion to high afternoon temperatures, the actual cause remains under investigation.

A magisterial inquiry has been ordered to establish what happened and fix responsibility. Prime Minister Narendra Modi has announced financial assistance for the victims' families, while Chief Minister Pinarayi Vijayan has offered to bring in medical experts from other states to treat the burn victims if necessary.

This event has raised urgent concerns about safety regulations in the firecracker manufacturing industry, which has a checkered history marked by deadly accidents. With call for regulatory reforms growing louder, the tragedy in Kerala underscores the need for immediate action.