At least 34 people were killed after several homes were crushed by a collapsed wall and a landslide triggered by heavy monsoon rains in India's financial capital Mumbai, authorities said Sunday.

Rainwater also inundated a water purification complex, disrupting supply "in most of the parts of Mumbai", a megacity of 20 million people, civic authorities said.

A falling tree demolished a wall in the eastern suburb of Chembur during Sunday's early hours, burying nearby residents, the National Disaster Response Force (NDRF) said.

Twenty-one bodies have been recovered from the rubble, it added late Sunday after wrapping up search operations.

"In the adjacent house, I saw a small girl who was trapped in the debris. She was shouting 'save me, save me'," Firoz Khan, who was caught up in the downpour in Chembur, told AFP.

"Her body was trapped in the mud. Somehow, I managed to pull her out. She had injuries in her legs. I narrowly survived this collapse."

Another resident, Manda Gautam Pradhan, said she had seen "rocks and mud... gushing down the hill along with the rainwater".

In the suburb of Vikhroli in the city's northeast, 10 people were killed after a landslide hit five homes early Sunday, the NDRF added.

Rescue workers inspect the rubble left after a falling tree demolished a wall in the suburb of Chembur, Mumbai
Rescue workers inspect the rubble left after a falling tree demolished a wall in the suburb of Chembur, Mumbai AFP / Sujit Jaiswal

Three other people were killed in separate incidents caused by the deluge, the Times of India reported.

Mumbai has been hit by downpours since Saturday, with local transport services affected.

The city's civic body did not say when the water supply was expected to be restored, but advised residents to boil the liquid before using it.

The Indian Meteorological Department said early Sunday that "moderate to heavy rain or thundershowers" were forecast for the next two days.

Prime Minister Narendra Modi tweeted his condolences and added that there would be financial compensation for victims' families.

Building collapses are common during India's June-September monsoon season, with old and rickety structures buckling under days of non-stop rain.

Last month, 12 people were killed when a building collapsed in a Mumbai slum.

And last September, 39 people died when a three-storey apartment block collapsed in Bhiwandi near the financial capital.