Two women were killed and over 15 injured when the staircase of the 80-year-old Palkhiwala building in Fort area of Mumbai collapsed on Friday morning.
Three people were still feared trapped in the debris, police sources said adding rescue operations were on.
Housing 32 tenants and 19 commercial establishments, the building had developed cracks, according to a resident.
Nearly 10 fire engines and two ambulances were pressed into service.
The rescue operations, carried out with the help of snorkels, were hampered due to the narrow passage and the falling debris. Several officers were forced to climb through the dilapidated structure to rescue the residents.
Meanwhile, the police claimed that the residents had applied for a no-objection certificate four months ago, which had been turned down. The building had undergone repair in 1981, they added.
The injured were undergoing treatment at St George Hospital and G T hospital.
The deceased were identified Saba Mansoor (15) and Vidya Jaiswal (32), the police said.