Calcutta, May 16: Twelve people collapsed one after the other and choked to death shuttered inside a popular garment store in Sodepur when welding sparks ignited a fire and burned up oxygen.

The fire broke out in Readymade Centre, a two-floor garment store in Sodepur on the northern fringes of Calcutta, at 12.10pm. Most of the 12 dead — 11 men and one woman —were shoppers, according to police sources. Over 20 people were injured.

The store has been a familiar fixture on Sodepur Road for years, growing floor by floor in step with the retail mania sweeping Bengal and the rest of the country.

Ironically, Friday’s fire was ignited by work aimed at further expansion of the shop. The shopping zone was being extended to cover the whole of the first floor. Sparks from a welding machine fell on a tarpaulin sheet and set it on fire, causing a macabre tragedy in the middle of the busy shopping season ahead of next month’s jamai sasthi.

The blaze in itself was not that intense but a controversial decision to pull down the shutters — cited reasons vary from preventing the fire from spreading to pre-empting possible flight of shoppers with garments — seems to have caused the maximum damage.

All casualties were because of asphyxiation and the bodies bore no burn marks.

“None of the deceased had burn injury marks. Everyone died because of lack of oxygen in the bloodstream and subsequent fluid accumulation in the lungs,” said Jagadish Halder, the acting deputy superintendent of Panihati State General Hospital, where six were brought dead. “The bodies had turned white and started swelling,” he added.

“The leaping flames prompted us to pull down the shutters to stop it from entering the shopping zone,” an employee of Readymade Centre told The Telegraph.

But the flames sneaked past the shutters through the AC duct and raced to the storeroom, which was stashed with inflammables like garments, paper boxes and plastic bags.

At least 35 customers — the store usually draws around 1,000 a day — were then shuffling through lines of garment collection in the 2,000-sqft, centrally air-conditioned first-floor shopping zone.

The fire that crawled around the shoppers unseen through the opaque AC duct was noticed by them when smoke and fumes started gushing in from the storeroom.

“We heard a woman and a man screaming ‘fire’ and some men running inside. We realised something was wrong and we jumped to the rescue,” said Pintu Biswas, a youth who runs a tea stall nearby.

Eyewitness later said people gasped for breath and collapsed soon after.

Among the dead was Gobinda Talapatra, a schoolteacher who had gone with his wife Rekha to the shop — around 20 metres from Calcutta’s oldest mall Sriniketan — to buy jamai sasthi gifts for their son-in-law and daughter. Rekha is now battling for life in a private hospital.

Narayan Saha, one of the store’s co-owners trapped inside the first-floor gas chamber, is also in a critical condition. His son Sankar, who ran into the shop when the fire broke out, is recuperating.

The fire was brought under control by seven fire tenders — not a large number — in an hour and a half with the help of people in the neighbourhood.

“It was not a case of usual fire breakout in a garment shop,” said a fire services official, suggesting that the casualties could have been averted had there been an opening for people to escape and oxygen to flow in.

The tragedy is certain to raise questions about safety measures and emergency response procedures in shops and malls mushrooming in the city and on its outskirts.

“The store had some fire extinguishers, but they did not function,” claimed a Sodepur Market trader who was part of the rescue operation.

“We have started a specific case after the officials of fire brigade lodged a complaint against the shop-owners,” said Supratim Sarkar, the superintendent of police, North 24-Parganas.