The 2013 El Reno tornado, which struck Central Oklahoma on May 31, 2013, remains the widest tornado ever recorded, reaching a staggering 2.6 miles (4.2 km) across. This rain-wrapped, multiple-vortex monster produced extreme winds exceeding 313 mph (504 km/h) within its sub-vortices—among the highest ever measured—though it mercifully stayed over mostly open terrain. The tornado's erratic and immense size proved deadly, killing eight people, including four storm chasers (the first known chaser deaths in history), among them renowned TWISTEX scientist Tim Samaras, his son Paul, and research partner Carl Young. Because it was rain-wrapped and moved unpredictably, dozens of chasers and residents were caught off guard, leading the National Weather Service to call it "the most dangerous tornado in storm observing history." The storm also threatened thousands of rush-hour commuters in Oklahoma City, and experts estimate that had it maintained its strength over the congested highways, more than 500 lives could have been lost. Due to its record-breaking size, ferocity, and tragic human toll, the El Reno tornado has become one of the most studied and infamous tornadoes in meteorological history.