Updated

Indian authorities braced for one of the world's largest religious gatherings with more than 10 million Hindus expected to enter the Ganges River early Monday to cleanse their sins in a festival held once every 12 years.

Naked ash-smeared holy men with long hair and beards and tridents in their hands were taking their positions for a massive procession to the riverbank in Allahabad where the Ganges joins the Yamuna River, and according to Hindu belief, the mythical Saraswati River. They plan to enter the water at the auspicious time of 5 a.m. amid the chanting of hymns and blowing of conch shells.

Masses of people, their hands clasped in prayer, will walk knee-deep into the frigid water, with temperature expected to dip to about 5 degrees Celsius (41 degrees F).

Devout Hindus believe bathing in the Ganges during the festival can cleanse their sins and free them from the cycle of death and rebirth.

More than 100 million pilgrims from India and abroad are expected to attend the 55-day Maha Kumbh festival, said Devesh Chaturvedi, an official of Uttar Pradesh state in northern India.

The festival derives its name from a Hindu belief that gods and demons fought over a pitcher, or "kumbh," of nectar that would give them immortality. The myth says one of the gods ran off with the pot, spilling four drops of nectar. Every three years, festivals are rotated among the four spots where nectar was said to have spilled. The Allahabad festival is considered the most blessed because it is near the confluence of the three rivers sacred to Hindus.

The festival area, covering 2,000 hectares (4,900 acres), has been turned into a tented township of green, blue and saffron-colored tarpaulins. More than 30,000 makeshift toilets have been set up.

About 50,000 government forces, including commandos, are providing security, police Inspector-General Alok Sharma said.