One of the injured received head injuries although doctors said his condition was stable.
Many more people, including family members of criminal lawyer Rizwan Merchant, were feared trapped under the debris.
Rescue operation was underway although it was being hampered by rain and traffic in the narrow bylanes.
The building, aged around 40 years, housed a car showroom on the ground floor while five-six families were residing in it. A local corporator said the condition of the house was good.
Fire brigade officials said the showroom owner broke the concrete base and the foundation pillars could not take the weight of the house, leading to the collapse.