Fire brigade officials said some nine families lived in the dilapidated Husaini Building. Some media reports said it also housed a play school but children had not arrived yet when the tragedy occurred.
The building, mostly housing lower-middle class families, was located in the Muslim-dominated Pakmodia Street near the J J Hospital.
The building, which also had six godowns on the ground floor, crumbled at around 8:30 am. It's not clear if the heavy rains that inundated Mumbai this week had weakened the building, said to be over 100 years old.
What remained was a large mound of concrete rubble and steel rods encircled by other houses including what appeared to be a tall building. Rescue workers in hard hats clambered up the mound and hammered at concrete slabs with hammers to reach underneath. Cranes and bulldozers were also deployed to scoop up the debris. Residents helped with bare hands.
"The exact number of trapped people cannot be known immediately," deputy commissioner of police (Zone 1) Manoj Sharma said.
