The explosion was caught on CCTV cameras.
One person died after a helium tank exploded when he was buying balloons from a roadside vendor at a busy market street in Tamil Nadu's Trichy on Sunday evening.
At least four people suffered minor injuries in the explosion. The victim was identified as Ravi, aged 35.
The police have arrested the balloon seller, Nar Singh, and have charged him with "causing death by negligence".
"A man who was buying balloons died on the spot. Four or five other people suffered mild injuries," a police officer told NDTV.
The explosion was caught on CCTV cameras placed in a textile showroom in the Fort area of the city, outside which the vendor sold balloons.
The video shows people running in all directions after the explosion. An autorickshaw and a few two-wheelers were also damaged in the blast.