Several houses have collapsed and it is feared victims could be trapped under the debris.
Authorities have reported 11 incidents of houses or walls collapsing in the Mumbai area in the last 24 hours. In one neighbourhood about half a dozen shacks located at the base of a hill collapsed on top of each other, officials said.
Rescuers were seen using their hands to dig up the ground and retrieve bodies and carrying the injured through narrow lanes on makeshift stretchers, local television showed.
Narendra Modi, the prime minister, offered condolences in a tweet and announced aid for the victims.
He said: “Saddened by the loss of lives due to wall collapses in Chembur and Vikhroli in Mumbai. In this hour of grief, my thoughts are with the bereaved families. Praying that those who are injured have a speedy recovery.”
He added, in a second tweet: “Rs. 2 lakh [200,000 rupees, or £1,950] each from PMNRF [Prime Minister’s National Relief Fund] would be given to the next of kin of those who lost their lives due to wall collapses in Mumbai. Rs. 50,000 would be given to those injured.”
Several areas in the city were flooded after heavy rainfall over the last 24 hours and suburban train services were disrupted, crippling India’s financial capital.
Mumbai and the coast of India’s industrial Maharashtra state are expected to receive heavy to very heavy rainfall in the next four days, the weather department said on Sunday.
Additional reporting by Reuters