A stampede at the world's largest religious gathering has killed at least 15 people with many more injured, a doctor at the Kumbh Mela festival in northern India said Wednesday.

Deadly crowd accidents are frequent occurrence at Indian religious festivals, including the Kumbh Mela, which attracts throngs of devotees every 12 years to the city of Prayagraj in Uttar Pradesh.

The six-week festival is the single biggest milestone on the Hindu religious calendar, and millions of people had traveled there to take a dip in the confluence of holy rivers.