Several people reportedly died at a religious festival in India when millions of Hindu devotees gathered for a ritual dip in a river.

Reuters news agency reported at least seven were killed and around 10 were injured in a stampede on early Wednesday at the Hindu "Kumbh Mela" festival.

The festival, said to be the world's largest religious gathering, began on January 13 in the northern state of Uttar Pradesh. Wednesday is the most auspicious date of the six-week festival.

A local man who took a ritual dip told NHK that people should not hurry. He said the crowd was very large and he thought it was unmanageable. He said a bath could take 5 hours.

"Kumbh Mela" takes place periodically, rotating among four holy sites in India. This year's gathering is being held in the city of Prayagraj, the holiest of the sites, for the first time in 12 years.

Local authorities say they expect about 400 million people to attend the festival, which goes on until February 26. This includes foreign visitors.

Similar accidents involving large crowds at religious gatherings have occurred frequently in India. More than 100 died in another Hindu event in Uttar Pradesh last July.