The incident took place yesterday afternoon when the two girls, identified as Poonam (16) and her elder sister Neha (17), were sitting with their two-year-old niece Tamanna outside their neighbour's house in C-Block of Sultanpuri.
According to the two sisters, the balcony on the first floor of the building collapsed on them while they were sitting under it at around 12.30 P.M., when some labourers were doing construction work in the house.
Doctors said the death was caused due to head injuries which were sustained by Tamanna, the only child of her parents.
Hospital authorities informed police, who have registered a case of causing death due to negligence against Shakuntala, the owner of the house. However, she was untraceable till this evening.