A six-year-old boy was killed and four of his family members were seriously injured in an explosion in a snack shop on Prince Anwar Shah Road, opposite the Odyssey store, on Sunday evening.

Police and fire brigade officials were not sure what caused the explosion but suspect that heat from a kerosene stove in the shop blew up a carbide cylinder, used for welding.

“We are trying to ascertain the cause of the explosion and find out whether the shop had licences,” said Ajey Ranade, the superintendent of South 24-Parganas police.

According to police, Sheikh Bablu, aged about 50 years, ran the shop. He was injured along with his wife Ajmira Bibi, 45, daughter Pinky, 24, and her son Shamim, 7.

Sohail, Pinky’s younger son, was declared dead at the hospital. Pinky’s husband Raju Khan, 30, was near the shop but was not injured. All six family members lived in a shanty in Hoglapara, near Navina cinema hall.

Two fire tenders rushed to the spot after the mishap around 6.30pm. The area, at the mouth of a congested lane leading to the Hoglapara slum, was cordoned off on the suspicion of a gas leak.

“The injured have been admitted to MR Bangur Hospital. They will be interrogated after they recover. The boy’s body has been sent for post-mortem,” added Ranade.

Bablu used to work as a welder in a local garage. The garage had shut down a year back. Since then he used to take up welding work that came his way since he was not earning enough from the shop to sustain the family, with Raju being unemployed. Hence Bablu’s welding equipment, including two cylinders containing highly combustible gasses, were kept in the shop.

Residents told police that the adult family members were working near the stove in the shop while the two children were playing near its entrance.