A fire broke out at the Dum Dum distribution station of CESC on Friday morning, forcing residents in adjacent buildings to evacuate and triggering allegations of a late response by the fire brigade.

A six-storeyed residential building with 17 apartments on Jessore Road had to be vacated. Residents feared a disaster as the leaping flames started damaging air-conditioning units.

The CESC unit caught fire around 11.30am after one of the two transformers on the premises had exploded. Firemen fought for three hours to control the flames.

The distribution station on Jessore Road, near Gorabazar, is one of the 106 units of CESC across the city. It receives power from the grid and distributes it to a particular area.

"We replaced an old 33KV transformer with a new one, which was commissioned on Friday. The explosion took place as soon as its power generation switch was turned on," a CESC official said. "The condition of the other transformer is yet to be ascertained."

Fire department officials are yet to ascertain the reason behind the explosion.

Two tenders reached the spot from the fire station at the nearby Gun and Shell Factory but the capacity of their water-tanks was not adequate. Both turned back.

Residents alleged that tenders from the Maniktala, Panihati and Dum Dum fire stations arrived around 1pm, one-and-a-half-hours late.

When asked about the delay, a fire department official said: "Our men left for the spot as soon as they were alerted. They took time to reach because of traffic congestion."

Ratan Manna, a trader in the area, said traders and local youths initially started sprinkling water on the flames. "But we had to stop as the heat soon became unbearable. The fire brigade was repeatedly called but they were not coming," Manna said.

A fire department official said the blaze spread fast because of the fuel in the transformer that exploded.

Shilpi Majumdar, a homemaker in her late 40s, said she was in a state of shock seeing the flames leaping higher than her third-floor apartment (see graphic).

"I decided to keep my cool. My first priority was to escort my 92-year-old father-in-law, who can't move on his own, to safety," she said.

Shilpi and other occupants of the six-storeyed building had all vacated their apartments.

Subir Chakrabarty, an assistant general manager of Calcutta airport, said his fifth-floor apartment was empty when the fire broke out because his wife had taken her daughter to a doctor.

"Neighbours told me that the flames had reached the fifth-floor walls of the building's northern and eastern portions. I reached the spot and saw the firemen were unable to control the blaze. I immediately contacted the airport authorities and asked them to send fire extinguishers with foams," Chakrabarty said.

The fire had disrupted traffic on Jessore Road. Vehicular movement had to be suspended for an hour as the CESC unit's proximity to a petrol pump had sparked fears of an explosion.

The airport-bound flank of the thoroughfare near the spot was closed for six hours.

‘I was numb with fear that the blaze would swallow our building’