A fire broke out in the office of a nationalised bank on the first floor of Shantiniketan Building, on Camac Street, on Tuesday morning.

Witnesses said black smoke started emanating from the 15-storeyed building around 6.20am. No one was injured.

"The fire-safety mechanism in the office of the State Bank of Patiala was partially defunct and in the rest of the building, it was dated," said an official of the fire and emergency services department.

Four tenders took two hours to douse the blaze, which fire department officers said broke out in the bank's server room.

The bank's furniture - including a big sofa in the customer lounge area, the false ceiling, wooden partitions of the cubicles - as well as several desktops and air-conditioners were charred. The fire department sealed the office for an indefinite period.

A man who identified himself as an official of the bank but refused to be named said the cash and digital details of the customers were unaffected.

Radio jockey Mir reached Shantiniketan Building, which houses his office, within minutes of the fire breaking out.

"The first floor of the building caught fire around 6.20am. I reached there within 5-10 minutes. It was a scary sight. The northwest wing of the first floor was in flames. There were not too many people inside at that early hour," Mir said.

"The fire engines arrived by 6.35am. I was there throughout and had the unique experience of Whatsapping contents to my engineer and we managed to broadcast the situation live. The lifts are closed for the next couple of days... so good news for people who want to lose weight! I think this is a wake-up call for all old buildings in Calcutta to take precautions."

Two guards who were inside the bank when the fire broke out rushed out and alerted everybody.

Those who were inside the building - mostly guards and caretakers - were evacuated and the electricity connections snapped. "The guards who were inside the bank said the fire alarm went off but the water sprinklers did not work. That is why the place was gutted," said an officer who supervised the fire-fighting operation.

Forensic experts collected samples form the bank.

"The fire seems to have originated in the server room of the bank. It might have been simmering for some time before it was detected. We had to break several windowpanes to let the smoke out," the fire department officer said.

Shantiniketan Building is barely a kilometre from Chatterjee International Centre and Himalaya House on Chowringhee Road, where fires broke out over the past six months.

Firemen said some of the extinguishers in the building were past their expiry dates and several water hydrants were defunct. They also alleged that smoke alarms and water sprinklers were not installed in corridors and staircases. "The centralised fire-fighting system, a must in such a highrise, is defunct," the officer said.

Representatives of the building's management could not be contacted.