NEW DELHI (AP) — Tens of thousands of people at a massive religious gathering in India rushed to take a holy bath in the country's northern Prayagraj city, setting off a stampede early Wednesday that injured dozens, local media reported.

It was not immediately clear what triggered the panic at the Maha Kumbh festival where devotees had congregated from across India to bathe at the confluence of the Ganges, the Yamuna and the mythical Saraswati rivers. News agency Press Trust of India cited authorities who said injured were sent to a hospital.

The Maha Kumbh festival, held every 12 years, started on Jan. 13 and has been touted by Indian authorities as the world’s largest religious gathering. Authorities expect more than 400 million people to throng the pilgrimage site in total over the next six weeks.

Stampedes are relatively common around Indian religious festivals, where large crowds gather in small areas with shoddy infrastructure and few safety measures.