There were no casualties in the fire that started from a house at 2 am on Jamnalal Bajaj Street and soon engulfed nearby buildings and commercial establishments housing cloth and tarpaulin shops in the area, said Fire Services Minister Pratim Chatterjee.
He said that at least 40 fire tenders were pressed into service to douse the flames which continued to rage even 12 hours after it broke out.
The Minister said the fire brigade had reached the spot at two o'clock but could not immediately begin the work owing to a power cut in the area and shortage of water supply.
"Our men could finally begin work around 3 am," he said, adding that most of the buildings in the area were hoarded with inflammable materials like plastics, clothing materials and tarpaulin.
Police said all buildings in the area were evacuated as a precautionary measure and the Mahatma Gandhi Road, connecting Howrah station with the Sealdah Terminus, has been closed to traffic.
A high-level committee would be set up to probe the cause of the fire, Chatterjee said.