Another 26 were hospitalized, a hospital spokesman said.
Dozens more were feared trapped in the rubble of the old residential building in southern Mumbai, CNN reported.
"It's a pancake collapse. The exact number of those trapped under the debris is not known," said Sachidanand Gawde, deputy commandant at the National Disaster Response Force.
He said 31survivors had been pulled from the debris.
Vijay Khabale Patil, a spokesman for the Brihanmumbai Municipal Council, which owns the building, said a notice was issued in April concerning major structural issues and the building has undergone major renovations, with more repairs had been scheduled.
The first floor of the building was occupied by a decorating firm, but about 22 apartments were on the upper four floors, Brihanmumbai Municipal Council member Sitaram Kunte said.
"There is a lot of chaos here, but my boys are closely monitoring any noises or movement from under the debris that can lead us to people trapped inside," Gawde said. "We are using latest rescue techniques so that maximum number of lives could be saved."
India Today Online reported the building, which had housed civic employees, was at least 50 years old. The report said most of the residents were asleep when it came down.
A few years ago, the building was declared dilapidated and inspectors recommended moving residents to another location while repair work could be carried out, the report said.
Seventy-four people died in the collapse of a suburban Mumbai building in April, The New York Times reported. A residential building fell in June, killing six.