The fire was noticed at around 9.50 PM in the third floor of the heritage building, the office of The Statesman newspaper, during the peak hours of news operation.
Eight fire tenders reached the spot and brought the blaze under control in an hour, the officials said.
Smoke billowing from the house has engulfed a major area.
Employees of the newspaper were evacuated from the 130-year-old building, considered a major landmark in the city.
Fire Minister and City mayor Shovan Chattopadhyay rushed to the spot to supervise the fire fighting operation.
A major fire in 2006 had damaged some rooms in the ground and first floor of the building.