A 23-metre (60-foot) high wall collapsed on a cluster of tin-roofed huts in western India early Saturday following heavy rains, killing at least 16 workers and their families living there.
The wall dividing the car parking area of a multi-story residential apartment building collapsed in Pune, a city in Maharashtra state, fire officer J Gaekwad said.
Rescuers pulled out alive three workers from the rubble, he said. The operation was continuing as more people could be trapped under the debris.
The workers were employed at an adjacent construction site, according to the Associated Press.
Separately, three people were electrocuted in Mumbai, the financial and entertainment capital of India, as delayed monsoon rains hit Maharashtra state on Friday, the Times of India newspaper reported.
Building collapses are common in India during the June-September monsoon season, when heavy rains weaken the foundations of structures that are poorly constructed.