The tornado that ripped through Nebraska on Friday, injuring 15 people and flattening buildings, may have reached a wind velocity of up to 320 km/h, the USA National Weather Service said on Saturday. It was part of an unusual early autumn storm system that also dropped 92cm of snow in South Dakota and Wyoming, where a 610 km stretch of Interstate road 90 was still closed on Saturday.

The twister struck the small town of Wayne in northeast Nebraska on Friday. It damaged about 10 homes and two dozen businesses in Wayne, according to Nebraska Emergency Management. The tornado produced EF2 to EF3 damage in Wayne and possibly EF4 damage at a business park there, the National Weather Service said. An EF4 tornado has wind speeds of 268 to 322 km/h, according to the weather service. Images taken by the Nebraska state patrol.

Twisters also swept through parts of Iowa, destroying more than 20 homes and damaging 40 to 60 farms, said Woodbury County Emergency Management Director Gary Brown.