Okklahoma tornado

Tornadoes can kill, and the Tri-State tornado was the deadliest of them all

http://www.guardian.co.uk/world/shortcuts/2013/may/21/tri-state-tornado-deadliest-of-all

Why was the Oklahoma tornado so dangerous?

http://www.guardian.co.uk/world/2013/may/21/why-oklahoma-tornado-so-dangerous 

Oklahoma tornado – in pictures

http://www.guardian.co.uk/news/2013/may/21/oklahoma-tornado-key-pictures-day