Ruby Chakraborty breaks down outside a Sodepur nursing home, while conveying to her family the news of the death of her brother in the garment store blaze. Picture by Sanat Kumar Sinha

Two 10ftx8ft shutters converted the first floor of Readymade Centre into a 2,000-sq-ft gas chamber on Friday afternoon.

Trapped inside, shoppers and staff of the garment store gasped for breath and inhaled toxic fumes billowing out of burnt garments and plastic bags for over 15 minutes till the shutters were pulled up. The 35 shoppers and employees were barely conscious by then.

Late on Friday, 12 of them had died and the others were fighting for their lives.

“None of the 12 died of burns; carbon monoxide poisoning killed them. The tragedy could have been averted if the shutters had not been pulled down,” said a doctor at Panihati State General Hospital, where the first batch of patients were taken.

While there were rumours that someone from the store had pulled down the shutters to prevent shoppers from slipping out with garments, the police and the firemen chose to play safe.

“We have heard such allegations and are conducting a probe,” said a senior North 24-Parganas police officer.

Around 3.30pm, a four-member forensic team visited the spot and spoke to employees of the store to figure out how people were trapped inside. The investigators collected evidence among charred remains on the first floor.

“We cannot comment before completing our inquiry,” said a forensic officer.

The rubble outside Sodepur’s Readymade Centre, site of 12 deaths in a blaze on Friday. Picture by Sanat Kumar Sinha

With Narayan Saha, one of the owners of the store, and his son Sankar (Rana to his near ones), injured, employees of Readymade Centre were reluctant to speak.

A staff member told Metro on condition of anonymity that pulling down the shutters was a panic reaction. “The flames leapt to the first floor after the tarpaulin caught fire. To ensure that the fire didn’t spread to the shop floor, we pulled down the shutters,” said the middle-aged man.

Within minutes, the employees realised that it was a mistake. “The flames shot through the air-conditioner duct running across the shop floor to the storeroom at the back. Everything inside the storeroom was inflammable. The shop floor became a smoke chamber and people started screaming for help,” the employee added.

Other employees and residents came running to the first floor after seeing the smoke and the flames. But pulling up the shutters had become difficult, with the fire engulfing the approach.

“When we finally went inside, we could hardly see anything. The room was full of thick, black smoke and people were groaning. So many would not have died if the shutter was kept open,” said Ajay Biswas, a resident of neighbouring Railway Park.