At least 35 people were killed and 16 were grievously injured after the roof of a stepwell in a temple complex collapsed in central India according to a local government official Friday, with rescue operations still underway in an attempt to locate the one missing person.

Dozens of worshippers celebrating a major religious holiday plunged into the stepwell – a stair-lined communal water source – on Thursday after the floor covering it collapsed in the central city of Indore.

"We have 35 people dead. One person is still missing. Rescue operations are on," Indore district magistrate Ilayaraja T. said.

A witness at the scene said that rescuers were working to determine whether or not one more person reported missing had also fallen down the well.

Women, children and an 18-month-old baby were among those standing on the grill covering the well when it buckled and gave way, plunging them into about 7.5 meters (25 feet) of water, The Times of India newspaper reported.

Prime Minister Narendra Modi on Thursday said he was "extremely grieved" by news of the accident.

"The state government is spearheading rescue and relief work at a quick pace. My prayers are with all those affected and their families," he added.

Modi's office said compensation payments of 200,000 rupees ($2,400) would be given to the next of kin.

Narottam Mishra, home minister of Madhya Pradesh state, told reporters on Thursday that an investigation had been launched into the mishap.

Television footage on Thursday showed emergency workers using ropes and ladders to reach those trapped in the well in Madhya Pradesh province.

Other videos showed the caved-in floor and mangled steel bars, as well as police officers, used ropes to seal the area.

Temples across India were brimming with devotees on the occasion of Ram Navami, the birthday of the Hindu deity Lord Ram.

Deadly religious accidents

Deadly accidents are common at worship sites in India during major religious festivals.

At least 112 people died in 2016 after a huge explosion caused by a banned fireworks display at a temple marking the Hindu new year. The blast ripped through concrete buildings and ignited a fire at a temple complex in Kerala state where thousands had gathered.

Another 115 devotees died in 2013 after a stampede at a bridge near a temple in Madhya Pradesh. Up to 400,000 people were gathered in the area, and the stampede occurred after the spread of a rumor that the bridge was about to collapse.

About 224 pilgrims died and more than 400 others were injured in a 2008 stampede at a hilltop temple in the northern city of Jodhpur.