EXPLAINER: Here is why crowd surges can kill people

NEW YORK (AP) — The crowd deaths at a Houston music festival added even more names to the long list of people who have been crushed at a major event.Tragedies like the one Friday night at the Astroland Music Festival have been happening for a long time. In 1979, 11 people died in a scramble to enter a Cincinnati, Ohio, concert by The Who. At the Hillsborough soccer stadium in England, a human crush in 1989 led to nearly 100 deaths. In 2015, a collision of two crowds at the hajj pilgrimage