The Kanwar Yatra is an annual pilgrimage in the name of the Hindu god Shiva. The devotees leave their hometowns either on foot, by bike, motorbike or truck and head for Haridwar to collect holy water from the river Ganges which they then carry back to their hometowns. Since the 1990s the festival has gained a massive following and now attracts hundreds of thousands of pilgrims from the surrounding states.
Wikipedia states
During festivals, Haridwar is packed to bursting and beyond. Stampedes are a regular occurrence, with 21 killed in 2003 and 5 killed in 2010; the bridges across the Ganges are the most dangerous spot.