How in hell can this happen? Better part of a thousand folks stampeded to death at Hajj

sauce: http://www.bbc.com/news/world-middle-east-34346449

At least 717 people taking part in the Hajj pilgrimage have been killed in a stampede near the Islamic holy city of Mecca, officials in Saudi Arabia say.

Another 863 people were injured in the incident at Mina, which occurred as two million pilgrims were taking part in the Hajj's last major rite.

Maj Gen Mansour al-Turki, a spokesman for the Saudi interior ministry, said the crush occurred when two large groups of pilgrims converged from different directions on to one street. (Duh. This could have been averted if someone assigned crowd flow directions ahead of time.)

It is the deadliest incident to occur during the pilgrimage in 25 years.
Preparations for the Hajj were marred when a crane collapsed at Mecca's Grand Mosque this month, killing 109 people.

That was a terrible incident. I used to wonder how people could be trampled in a crowd up until I was leaving a Saints game over in New Orleans a few years back. I was very uncomfortable because there was nowhere to go but with the crowd and we were being pushed very quickly by the people behind us to get out of the Superdome. It's something I will never forget. I can see how people can panic and try to fight against the crowd. I also heard that some people were leaving while others were coming in during the incident this week. Just a rope barrier could have stopped all those deaths.
Hindsight is always 20/20 though.