A human tragedy was narrowly averted when Nicco House, a landmark of the city’s business district, caught fire on Friday afternoon while 1,200 employees of 100-odd offices spread across six floors were at work.

Panic-stricken people came running down the stairs carrying stacks of documents, laptops and even desktop computers as smoke billowed out of a room adjacent to the second-floor canteen around 2.30pm and the flames spread rapidly.

Fire brigade personnel rescued 15 people trapped on the second floor. “It was a big blaze. We needed 25 fire engines and three-and-a-half hours to prevent the flames from spreading beyond the second floor,” a fireman said.

Officials said an electrical short circuit or something in the canteen might have triggered the fire.

The director of fire services, Gopal K. Bhattacharya, said the 60-year-old building was a tinderbox. “We were shocked by the level of carelessness. The offices comprise rows of cubicles with false ceilings. Plywood has been used everywhere possible and the corridors have been almost blocked with furniture and stationery.”

It was the third fire at the seven-storeyed Nicco House in eight years, sources said. “The owners were given a list of fire-prevention measures after the blaze eight years ago, which they ignored. They do not have a fire licence,” Bhattacharya said.

An office of Nicco UCO Alliance Credit Ltd on the southern wing of the building — located at the intersection of Hare Street and Church Lane — was partially gutted.

“An accident like this was waiting to happen. Thankfully, there were no casualties,” said fire services minister Pratim Chatterjee.

Udayan Ray, the managing director of Nicco Corp, declined comment on the allegation that the building didn’t have a proper fire-prevention system. “All I can say is that the fire is under control now. There is no power and nobody is allowed inside. We can only assess the extent of damage on Saturday.”

For those who were on the upper floors of the building when the blaze was detected, the shouts of “fire…fire” will ring in the ears for some time. “My colleagues and I rushed out with the computers and official documents that we could carry. Around 3.30pm, I took a risk and returned to my fifth floor office in the southern wing to extract the hard disk of our main computer server,” said Swarup Saha, the project manager of Dawsen Infotech Private Ltd.

Most of the employees stayed put on the pavements around the building till the flames were put out. Partha Mazumdar, senior adviser to Gujarat Tea Packers and Processors Ltd, said: “I was in my third-floor office when the fire broke out. I looked down from a window and saw smoke just below me. There were around 12 of us in our office. We were evacuated around 3pm. A lot of lives could have been lost.”

A false ceiling made of plywood in the Nicco UCO Alliance office hampered the firefighters’ efforts. “We had to go up to the third floor and drill a hole in the false ceiling to spray water. The office being centrally air-conditioned meant there was lack of ventilation,” a fireman said.

Companies that are a part of Nicco Corp occupy the first, third and sixth floors of the building. The other offices include those of tea firms.