Firemen carry out rescue operations after the second and first floor balconies of the inner courtyard of Rani Rashmoni’s house in Janbazar collapsed on Wednesday afternoon. Picture by Sanjoy Chattopadhyaya

Fifteen residents of one of Rani Rashmoni’s properties in Janbazar, at 18/3A, SN Banerjee Road, were trapped for about an hour on Wednesday afternoon when the second and first-floor verandahs surrounding an inner courtyard collapsed.

The heritage building was constructed in 1877 and belonged to Peary Mohan Choudhury, son-in-law of Rani Rashmoni. Peary had married her daughter Kumari.

The building is inhabited by descendants of Peary Mohan who have been living there for six generations. It has a thakurdalan surrounded by verandahs emblazoned with large medallions bearing the profiles of beauties in stark black and white.

As in other years, Durga puja was held here this time, too, and many women of the family were huddled on the thakurdalan steps after the accident. Dibyendu Choudhury, a man in his thirties who had received minor injuries, was in a state of shock after he and other trapped residents were rescued by firemen.

Family members said a large water tank on the third floor had collapsed around 3.30 pm and the ancient building, not in good repair, could not bear its impact. The verandahs in the andarmahal, or living quarters, gave in, blocking a staircase.

Following consultation with the heritage wing of the Calcutta Municipal Corporation, director-general (building) Gorachand Mondol ordered demolition of the portions in a precarious state. “Reconstruction will be allowed only if it is in keeping with the architecture of the structure,” Mondol said.

Civic engineers suspect that illegal construction of the water reservoir on top of the roof two years ago resulted in cracks developing in the arches supporting the roof.

The continuous rain for the past few days — culminating in Wednesday afternoon’s downpour — could have weakened the structure. The weather office recorded 53.5 mm rainfall between 8.30 am and 5.30 pm on Wednesday at Alipore.

“From the wind flow pattern, we think there will be heavy incursion of moisture during the next 24 hours, leading to more rain,” said G.C. Debnath, director of weather section at the Regional Meteorological Centre in Alipore.