The Monday disaster in Patna, capital of eastern Bihar state, occurred during the annual "Chhath Puja," the state's largest festival during which Hindus gather along the banks of their sacred Ganges River to offer prayers to the sun during setting time.
The Press Trust of India news agency said the stampede started when a makeshift bridge at the river's Adalatghat bank gave way, causing panic among the people.
The Times of India newspaper, quoting officials, said at least 22 people, including 17 children, died in the disaster and another 40 people were injured, some of them critically, raising fears among authorities that the death toll could rise.
Bihar Chief Minister Nitish Kumar, who was visiting the various bank sites at the time of the stampede, expressed shock and ordered an investigation into the incident, the report said.
Rescue efforts were hampered by a shortage of doctors and paramedical staff, the report said. Angry mobs raised slogans against the government.