A massive fire erupted early Sunday at the multi-storey building, which houses nearly 1,000 business establishments, in the congested Bagree Market here.
No loss of life has been reported but two firefighters suffered minor injuries during the operation to douse the blaze, the fire department said.
The market is around a kilometre away from the Writers' Building and the Reserve Bank of India office, a senior fire official said.
Director general of West Bengal Fire and Emergency Services, Jagmohan, said it will take 24 to 48 hours to douse the blaze.
"We need time to contain the flames as four to five floors of the building are completely engulfed in fire. The shops were stacked with inflammable materials like plastic toys, deodorants, fabrics and chemicals," he said.
Thirty fire tenders have been pressed into service to douse the fire at the over 60-year-old building.
"We are doing our best to tackle the situation. Initially, water was sprayed from the outside. But now, we have managed to enter the building. Also, two firemen have received minor injuries during the operation," Jagmohan said.
The fire which broke out around 2.30 am on the ground floor of the building on Canning Street quickly spread to the other floors, he said.
"As the area is very congested, we are finding it difficult to work. We are using ladders and gas cutters to enter the building through window grills. A forensic team will be visiting the site soon to ascertain the cause behind the incident," the senior fire official said.
Chief Minister Mamata Banerjee, who left for business summits in Germany and Italy around 9.45 am, told reporters at the airport, "Nobody is trapped in the building."
Unconfirmed reports said people living on the top floor of the building managed to escape as soon as the fire broke out.
Located near Burrabazar area -- the commercial hub of the city -- the six-storey building has as many entry gates.
Fearing that the blaze may spread, people were also evacuated from adjacent buildings.
A few shop owners alleged that fire officials took time to start the operation. Some were also seen trying to enter the building forcefully but were stopped by police and fire department officials.
Anil Mehta, one of the shop owners, said, "I have lost everything in the blaze. My store, as well as the godown, has been gutted in the fire."
Mayor Sovan Chatterjee, who reached the spot along with senior police officers and Kolkata disaster management group (DMG) officials, told reporters that market authorities had not installed fire safety equipment despite warnings.
"We have visited Bagree Market several times and asked the shop owners to take precautions. The fire department had also recommended steps in this regard. However, no such measures were taken," he said.
Asked if he would take any action against the defaulters, the mayor replied in the affirmative.
"The incident could have been averted if safety measures were taken on time. The market authorities will be held accountable for the blaze. As of now, we are trying our best but fire fighting operation is tough here because of the sheer number of buildings," he stated.
Traffic restrictions have been imposed in the area.
"Due to a fire incident, Rabindra Sarani in between MG Road & Podder Court and Canning Street in between Brabourne Road & Rabindra Sarani are closed to traffic," the Kolkata Traffic police department tweeted.
