It happened at a music festival in Houston, a soccer stadium in England, during a hajj pilgrimage in Saudi Arabia, in a Chicago nightclub, and countless other gatherings: Large crowds surge toward exits, onto playing fields or press up against a stage with such force that people are literally squeezed to death.
And it has happened again, during Halloween festivities in the South Korean capital Seoul, where a crowd pushed forward, the narrow street they were on acting as a vice, leaving more than 140 people dead and 150 more injured.
