The massive EF4 tornado that touched down Monday Afternoon (May 20) in Moore, Oklahoma - southwest of Oklahoma City -  is likely to be one of the worst in history.

The tornado starting out as a funnel, but quickly turned into an enormous mile-wide wedge tornado. At least two schools were in the path of this devastating tornado.

An EF4 tornado, such as this one, produces wind speeds of anywhere from 166-200 miles per hour.