The powerful tornado that wiped out multiple structures and killed a 30-year-old man in Minnesota on Wednesday has been rated an EF-4. 

The EF-4 rating was confirmed after a damage survey was completed by the National Weather Service, with estimated wind speeds reaching a violent 170 mph as the twister hammered parts of Grant and Otter Tail counties. 

It's the first EF-4 tornado in Minnesota since Aug. 7, 2010, when Wilkin County was hit by a twister that carved a path as wide as two football fields. 

The July 8 tornado was on the ground for 31 minutes, traveling nine miles and reaching a width of 650 yards. It touched town 6.5 miles west of Ashby and lifted 5 miles east of Dalton, the weather service said. 

An EF-4 is the second-strongest rating a tornado can have on the Enhanced Fujita Scale. 

• EF-0: 65-85 mph - light damage
• EF-1: 86-110 mph - moderate damage
• EF-2: 111-135 mph - considerable damage
• EF-3: 136-165 mph - severe damage
• EF-4: 166-200 mph - devastating damage
• EF-5: 200+ mph - incredible damage

The tornado strengthened along its path, starting as a weak tornado before quickly intensifying into a strong and violent tornado in southern Otter Tail County. It grew into an EF-2 as it moved through St. Olaf Township and across Beebe Lake, then "likely reached maximum EF-4 intensity after it crossed Hwy. 82 and destroyed a machine shop and yard on the downwind of it," the NWS damage survey said. 

Just after striking the machine shop and killing a 30-year-old man, the tornado reached its peak width and wind speed.