Dozens of worshippers celebrating a major religious holiday on Thursday plunged into the stepwell — a stair-lined communal water source — after the floor covering it collapsed in the central city of Indore.
"Thirty-five people are dead. One person is still missing. Rescue operations are on," Indore district magistrate Ilayaraja T. told AFP by phone.
Prime Minister Narendra Modi said Thursday he was "extremely pained" by news of the accident.
"The state government is spearheading rescue and relief work at a quick pace," he added. "My prayers with all those affected and their families."
Modi's office said compensation payments of 200,000 rupees ($2,400) would be given to next-of-kin.
Narottam Mishra, the home minister of Madhya Pradesh state, told reporters that an investigation had been launched into the mishap.
Police official Manish Kapooriya told AFP rescue efforts were continuing and that the injured were being taken to government hospitals for treatment.
Television footage showed emergency workers using ropes and ladders to reach those trapped in the well in Madhya Pradesh state.
Other videos showed the caved-in floor and mangled steel bars as well as police officers using ropes to seal the area.
MNA/PR