A concrete slab covering a well inside a Hindu temple in the central Indian city of Indore gave way on Thursday, killing 36 people and injuring 16 more.

“The major cause of deaths could be drowning because the well was 60 feet deep and there was much water in it,” a local official said, as cranes were brought in to assist the search for survivors.

The Indore Hindu temple incorporates a stepwell, a signature feat of Indian architecture that involves digging deep into the rocky ground of India’s arid regions to reach the deeply buried water table. As the name implies, stepwells feature flights of stairs to reach the deeply buried water supply, and the larger examples could be ornately decorated and used as temples or mosques. During rainy weather, the huge stepwell excavations become cisterns for holding rainwater. 

Thousands of stepwells were dug across India, but the practice fell out of favor under British rule because many of the smaller and cruder wells were badly maintained and deemed unhygienic, and modern technology later provided alternative methods of reaching the water table.

The Indore temple was exceptionally crowded on Thursday to celebrate the Hindu festival of Rama Navami, the birth of an incarnation of Vishnu, one of the most exalted of the Hindu gods. The celebration of Lord Rama’s birth is an exuberant event that follows a day of fasting.

The stepwell cover reportedly gave way while the celebrants were performing a havan, a ritual in which offerings are burned in a fire pit. At least 40 people were sitting or standing on the concrete slab when it broke.

“The stepwell was covered, but the slab covering it collapsed because of the crowd and extra load on it,” said Shivraj Singh Choudan, the chief minister of Madhya Pradesh, the state that includes Indore.

NDTV quoted local sources who said several municipal complaints have been filed against the unsafe 40-year-old stepwell cover, but the private trust that administers the temple resisted demolition orders, saying the temple’s worshipers would be offended.

Choudan said a magisterial inquiry has been ordered into the accident, and “action will be taken against those found responsible.”

“We are with the bereaved families in this hour of grief. Proper arrangements have been made for the treatment of the injured, the entire medical expenses will be borne by the state government,” he said.

“We have ordered an inspection of such step-wells and borewells across the state,” he added.

On Friday, Indore Municipal Commissioner Pratibha Pal said the local building inspector and a building code officer have been suspended.

Indian Prime Minister Narendra Modi said on Thursday he was “extremely pained by the mishap in Indore.” He announced compensation of 50,000 rupees (about $610) would be paid to each injured person, and 200,000 rupees (about $2500) given to the families of each deceased victim.