An estimated 300,000 Hindus had congregated to bathe downstream from the dam on the banks of the Narmada river near Dewas, 200km from Bhopal, to pray in the annual festival of ‘Bhootdi Aamavasya’, or ‘Moonless Night’. Water levels rose after the dam opened its gates and more than 150 people were swept away.

Several boats and divers are still scouring the water for survivors following the tragedy, which happened on Saturday.

State authorities said the incident occurred after the gates opened without warning. But officials at state-run Narmada Hydroelectric Development Corporation say the release was simply routine, and dam officials were unaware of the large crowd downstream.

The Madhya Pradesh government wants a report on the incident from the principal secretary in the water resources department within 15 days, and has offered compensation of US$2292 to the families of each victim, according to CBC News.

The Indira Sagar has a full reservoir level of 262.13m and is part of more than 3000 dams being built across Narmada river and its tributaries as part of the Narmada Valley hydro project.