Thunderstorm topples crane in Mecca, dozens killed.

[Greg Campbell]

High winds blew a crane down onto the crowded building, collapsing a section of roof and flattening over a hundred pilgrims.

http://abcnews.go.com/International/dead-mecca-crane-collapse/story?id=33689040

 

[Taylor Wright]

Wow, that second video is pretty graphic. What a sad deal. Death toll is up to 107 now.

http://www.bbc.com/news/world-middle-east-34226003

50 mph is not extraordinarily high, so I looked into what could have caused it. I found an article explaining how winds that are much lower than design tolerance (~100 mph) can cause tipping, if the crane fails to "weathervane" :

http://www.vertikal.net/uploads/tx_filelinks/tower-crane-weathervane.pdf