A rush in nightlife district in South Korea kill more than 150 people over Halloween weekend, crowd researchers explain how such tragedies can happen and what you can do to stay safe...
As images of lifeless bodies piled atop each other and queues of emergency workers pushing gurneys loaded with the dead circulated across social media, Koreans demanded answers and accountability...
By Choe Sang-Hun, Chang Che and John Yoon
in Seoul, South Korea