717 People Dead: What Caused The Hajj Stampede?

(CNN)A day after a deadly crush killed 717 people during the Hajj in Saudi Arabia, a critical question remained Friday: What caused the chaotic stampede?

Source : http://www.cnn.com/2015/09/25/middleeast/hajj-pilgrimage-stampede/index.html

717 people dead: What caused the Hajj stampede?
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717 people dead: What caused the deadly Hajj stampede?