At 2.6 Miles Across, El Reno Tornado Is Widest Ever Recorded [VIDEO]

The massive tornado that struck the community of El Reno, Okla. last Friday is believed to be the widest E-F5 tornado ever recorded in the U.S., according to the National Weather Service.

At its maximum, the tornado was 2.6 miles across with wind speed estimates of 296 mph, some of the fastest ever recorded on Earth.

Eighteen people, including four storm chasers, were killed in the storm. The storm's strength was initially measured as an E-F3, but the extreme wind speeds resulted in meteorologists upgrading the storm's severity to the maximum level.

The May 31 twister narrowly surpassed the previous record for the widest tornado, a 2.5-mile wide storm that struck Hallam, Neb., on May 22, 2004, according to NBC news.

Mobile radar units took measurements of the massive, killer storm as it roared south of El Reno on Highway 81, the NWS reported.

The El Reno storm struck less than two weeks after a tornado in Moore, Okla. killed 24 people. On May 3, 1999 a powerful tornado also hit the town of Moore, where Doppler radar estimated the storm's winds reached as strong as 301 mph - the highest wind speed ever measured on earth.

The El Reno storm was nearly as strong.

NWS also reported, via Twitter, that the 11-day span between the May 20 storm in Moore and the May 31 storm in El Reno was the shortest timespan between E-F5 tornadoes in Oklahoma history.