Police say at least 30 people were killed and many more injured in a stampede at the world's largest religious gathering as millions of pilgrims rushed to dip in sacred waters during the Maha Kumbh festival in northern India.

Grieving families in India are cremating their loved ones while others are caring for their injured relatives in hospitals a day after a stampede

It was not immediately clear what triggered the panic at the festival where devotees from across India had congregated to bathe at the confluence of the Ganges, the Yamuna and the mythical Saraswati rivers.

Hindu devotees and mystics have gathered in the northern Indian city of Prayagraj for the Maha Kumbh festival, which is the largest religious congregation on Earth.

People were trampled as pilgrims at the Maha Kumbh Mela, one of the world’s biggest gatherings, gathered where the Ganges and Yamuna Rivers meet.

Dozens of people were killed in a crowd crush at the world’s largest religious gathering in India early Wednesday, as tens of millions of devotees went to bathe in a river on one of the most sacred days of a Hindu festival.

The Kumbh Mela happens every 12 years at Sangam, the confluence of three sacred rivers - the Ganges (Ganga), Yamuna and the mythical Saraswati. Hindus believe that bathing in the sacred waters will cleanse them of sins and help them attain salvation.