A four-storey building in Mumbai's Dongri area collapsed on July 16.
Fire brigade, Mumbai Police and civic officials rushed to the site to carry out the rescue operation. Narrow roads, huge crowds and thickly populated areas hampered rescue operations.
Building collapses are common in India during the June-September monsoon season, when heavy rains weaken the foundations of structures that are poorly constructed.
Between 40 and 50 people are believed to be trapped in the rubble, Brihanmumbai Municipal Corporation's disaster management division said, adding that it has erected a shelter at a nearby girls' school for those rescued. "We heard people trapped in the debris shouting for help, but we were helpless because it was hard to move the beams and debris".
"We have been visiting the BMC (Brihanmumbai Municipal Corporation) for funds to fix the buildings".
The collapse of a decades-old multistorey building in Mumbai on Tuesday has revived focus on illegal buildings way past their sell-by date endangering lives in India's commercial capital, where finding an accommodation is a huge challenge.
As the building collapsed it sent shock waves shaking adjacent buildings.
Maharashtra chief minister Devendra Fadnavis said the building was 100 years old. It was Kesarbai building in Dongri which is a four-floor structure. Late on Tuesday evening, municipal commissioner Praveen Pardeshi visited the site and said his immediate priority was to rescue the trapped people.
"Its five years since the court orders, but the BMC has done nothing to evacuate all these 499 unsafe (C1) buildings and demolish them".
An eyewitness said the building collapse felt like a quake.
Mr Talpade said the families were asked to vacate the dilapidated building some time ago but they continued to live there. A team of the National Disaster Response Force (NDRF) also reached to help in rescue work.
-According to preliminary information, the building is over 100 years old.
-After the collapse, a part of the building was left standing.