A fire broke out on the premises of the landmark Dey’s Medical on Bondel Road around 4pm on Saturday. It took nearly three hours and 11 fire tenders to bring it under control.

Police said no one was injured. A firefighter, who complained of shortness of breath, had to be hospitalised.

The premises at 62 Bondel Road house the registered office and factory of Dey’s Medical Stores (Manufacturing) Limited. The police said the compound houses two wings.

Passersby said they first noticed thick smoke rising from the first floor of a three-storey building and alerted the police and fire department. By the time the first fire tenders arrived, smoke was billowing out. Within half an hour, it had engulfed the Ballygunge area, dotted with residential apartments and businesses.

The police cordoned off the zone, diverted Bondel Road traffic, and cleared smaller lanes to allow more fire engines to reach.

Residents of adjoining buildings evacuated their homes, carrying LPG cylinders.

“The factory was stacked with inflammable chemicals and agents used in drug manufacturing. The fire spread from one pocket due to these,” said a senior fire and emergency services officer. A part of the premises, where drugs and chemicals were stored, suffered considerable damage, the police said. Forensic experts will visit on Sunday.

No Dey’s Medical official could be reached for comment on Saturday.

Some workers said repairs had been ongoing at the factory over the past few days. “We had asked some workers to stop welding for a while, but they didn’t listen. The fire may have started during welding,” said a worker.

Dey’s Medical is steeped in history. The company’s website says founder Bhupendranath Dey bought eight bighas of land there in 1956 to build a factory and manufacture drugs. The first batch was produced within seven months of setup, following clearance from the Union health ministry.

Two years later, Dey invited Bengal’s then chief minister, Bidhan Chandra Roy — who had long supported his work — to formally inaugurate the factory on January 15, 1958. Roy’s signature is still preserved on the first page of the factory’s visitor book.