At least 23 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 July 18.

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 July 18's early hours, burying nearby residents, the National Disaster Response Force (NDRF) said.

Seventeen bodies have been recovered from the rubble, it added, with rescue operations ongoing.

In the suburb of Vikhroli in the city's northeast, six people were killed after a landslide hit five homes early on July 18, the NDRF added.

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

Mumbai has been hit by downpours since July 17, with local transport services affected.

The city's civic body did not say when the water supply was expected to be restored.

The Indian Meteorological Department said early on July 18 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.