At least 20 people in India's southern state of Andhra Pradesh died in a stampede on Tuesday around 08:00 a.m. local time as they gathered on the banks of the Godavari River to take a holy bath that's part of the Maha Pushkaralu celebrations.
Indian Prime Minister Narenda Modi said he was "deeply pained" by the tragedy.
The chaos unfolded when thousands of pilgrims rushed towards one of the gates on the river bank.
Tuesday marked the first day of the Maha Pushkaralu festival, a 12-day celebration of the 12 sacred rivers in India. An estimated 24 million people are expected to take part.
"The incident happened as the first set of worshippers were coming out of the river after taking a dip and then got in the way of others who wanted to be in the water at an auspicious time," AFP news agency quoted senior police official A Srinivasan Rao as saying.
Mass stampedes are fairly regular occurrences in India. In 2013, dozens were killed near a Hindu temple in the country's central state of Madhya Pradesh.