Dozens are feared trapped following the disaster at a construction site in the city of Pune, in the state of Maharashtra.
The 60-foot wall belonging to a residential building came down after almost non-stop rains in many parts of India, police said on Saturday.
At the base of the wall were many makeshift huts built for the workers at a nearby construction site in the Kondhwa area of the city.
When the wall came down it fell on the cheaply-made huts, crushing them.
Police say they fear the death toll will rise.
A residential official, Naval Kishore Ram, confirmed the wall collapsed due to heavy rainfall, and said those who died were mostly builders from Bihar and West Bengal.
He added that negligence by the construction company which built the wall is thought to be the main reason behind the tragedy.
Pune Police Commissioner K Venkatesham told reporters: “Firm action will be taken against those responsible.
“We will check whether proper permissions were taken and safety measures were followed.”