At least 12 labourers were killed here when a portion of a godown where chemicals had been stored collapsed following an explosion on Wednesday morning.

Those killed in the 11am accident had been packing readymade clothes in a unit adjacent to the section where chemicals had been stored in drums.

The explosion was so intense that it destroyed the wall separating the chemicals unit and the garments section and the roof caved in, workers and officials said.

The city fire brigade pulled out 12 bodies from under the rubble of the godown at Pirana-Piplaj road and rescued nine persons during the nine-hour operation that ended at 8.30pm. The deceased include five women.

The injured were taken to the Ahmedabad Municipal Corporation-run LG Hospital. The godown is located in an industrial area on the outskirts of Ahmedabad city.

The explosion also ignited a fire that spread to adjoining godowns, the officials said.

“Our operation has come to an end. We have pulled out 12 bodies from the debris. We have also rescued nine persons. The fire was doused within 30 minutes, the operation was mainly about rescuing people trapped in the rubble,” said chief fire officer M.F. Dastur.

“An NDRF team joined us in the evening,” he said, adding that the explosion had caused the damage and loss of lives.

“There was a fire but it was minor. The godown collapsed due to the explosion. We used concrete-breaker drills to break the slabs to pull out people,” Dastur said.

At least 24 rescue and fire-fighting vehicles were pressed into service after a call about “a minor fire and explosion” was received around 11am, he said.

“We have initiated an inquiry into the incident,” said deputy commissioner of police Ashok Munia.

While the exact cause of the explosion is yet to be ascertained, some local factory owners alleged that it took place in a boiler installed at the chemical godown-cum-processing unit.

Relatives of some of the deceased persons told reporters that their kin were not working in the godown where the explosion took place. “My mother worked at a readymade garments unit adjacent to the godown. Because of the explosion, the entire structure, including the adjoining place where my mother worked, collapsed,” a man said.

Prime Minister Narendra Modi offered condolences to the kin of the deceased.

“Anguished by the loss of lives due to a fire in a godown in Ahmedabad. Condolences to the bereaved families. Prayers with the injured. Authorities are providing all possible assistance to the affected,” he tweeted.

President Ram Nath Kovind also offered condolences. “Distressed to learn about the loss of lives in a fire that broke out in a godown in Ahmedabad, Gujarat. My thoughts and prayers are with the bereaved families. I wish speedy recovery for the injured,” he tweeted.

Gujarat chief minister Vijay Rupani announced an ex-gratia compensation of Rs 4 lakh to the kin of each of the deceased. He also appointed senior IAS officers Vipul Mitra and Sanjeev Kumar to conduct an inquiry, said a government release.