A deadly tornado that tore across southeastern North Dakota this summer has been upgraded to an EF5 with winds topping 200 mph (322 kph), the strongest classification of tornado and the first on American soil in a dozen years, meteorologists said Monday.

The June 20 twister in Enderlin killed three people and caused significant damage. At its largest, the tornado was 1.05 miles wide (1.7 kilometers) and carved a path across the prairie for just over 12 miles (19 kilometers). Meteorologists from the National Weather Service office in Grand Forks estimated the tornado’s winds reached 210 mph (338 kph), according to the newly released analysis.

“In the last kind of 12 years, there’s been several strong tornadoes that have come close, but there haven’t been known damage indicators at that time to support the EF5 rating,” said Melinda Beerends, meteorologist in charge at the National Weather Service in Grand Forks. “It’s hard sometimes to get tornadoes to hit something.”

The tornado destroyed numerous structures, including fully loaded rail cars and trees, leading to a comprehensive assessment of its damage. This case took longer than usual due to the unusual findings, as advanced assessments revealed significant impacts previously unrecorded.

The last recorded EF5 tornado occurred on May 20, 2013, in Oklahoma, claiming 24 lives. The Enderlin tornado, with its record-breaking impact, highlights the severity of weather phenomena in the U.S.