The ceiling of the second floor flat of the four-storey Veerati Building came crashing down on the residents living on the first floor last afternoon, they said.
Police said the 25-year-old structure was evacuated following the incident and as one of the concrete columns supporting it also developed cracks.
The injured have been identified as Ruksana Khan (32), Maya Rebari (2), Kunku Rebari (23), Shanta Rebari (21) and Saybi Rebari (47).
"Saybi and his family was taking a nap in the afternoon when the incident took place," said a family member.
The other 12 families who have been evacuated have been shifted to MMRDA's rental housing scheme.