The tragedy occurred on Monday evening after Bon Om Touk, a festival marking the end of the rainy season. Prime Minister Hun Sen said it was 'the biggest tragedy in more than 31 years after the Pol Pot regime', referring to the murderous government of the 1970s.

Who?

Up to 2 million people had been predicted to attend the festival. As they started crossing a suspension bridge back to the capital, a group of about 10 people fainted. People believed they were electrocuted.

Why?

Why did people panic? While believing a few people had been electrocuted, some were taken by surprise by the bridge, which is designed to sway, but they thought it was broken.

How?

How did the authorities respond? Police sprayed water so that survivors could drink. As the crowds were slowly cleared, police photographed victims so that relatives could identify them. The water under the bridge was to be searched for bodies, as many people jumped or fell off the bridge. Today has been declared a day of mourning.

Where?

The worst crowd disasters in recent years include stampedes during the Muslim pilgrimage to Mecca, Saudi Arabia; in Hindu temples in India; and after soccer matches in Ghana and Guatemala.