EXPLAINER: How and why do crowd surges turn deadly?


              FILE - In this Sunday, Sept. 20, 2015, file photo, Muslim pilgrims pray at the Kaaba, the cubic building at the Grand Mosque in the Muslim holy city of Mecca, Saudi Arabia. The crowd deaths from a Halloween festival in Seoul, South Korea, on Saturday, Oct. 29, 2022 have added to the long list of people who have been crushed at a major event. Such tragedies have been occurring around the world for a long time at concerts, sports events and religious gatherings.   (AP Photo/Mosa'ab Elshamy, File)
            
              FILE - Stewards and supporters tend and care for wounded supporters on the field at Hillsborough Stadium, in Sheffield, England, April 15, 1989. The crowd deaths from a Halloween festival in Seoul, South Korea, on Saturday, Oct. 29, 2022 have added to the long list of people who have been crushed at a major event. Such tragedies have been occurring around the world for a long time at concerts, sports events and religious gatherings.  (AP Photo, File)
            FILE - Travis Scott performs at Day 1 of the Astroworld Music Festival at NRG Park on Friday, Nov. 5, 2021, in Houston. The crowd deaths from a Halloween festival in Seoul, South Korea, on Saturday, Oct. 29, 2022 have added to the long list of people who have been crushed at a major event. Such tragedies have been occurring around the world for a long time at concerts, sports events and religious gatherings.  (Photo by Amy Harris/Invision/AP, File) FILE - A security guard and an unidentified man look at an area with shows and clothes strewn around where several people were killed and others injured, as they were caught in a surging crowd entering Cincinnati's Riverfront Coliseum for a Who concert on Dec. 3, 1979.  The crowd deaths from a Halloween festival in Seoul, South Korea, on Saturday, Oct. 29, 2022 have added to the long list of people who have been crushed at a major event. Such tragedies have been occurring around the world for a long time at concerts, sports events and religious gatherings. (AP Photo/Brian Horton, File)