A tornado that ripped through Nebraska, injuring 15 people and flattening buildings, may have reached a wind velocity of up to 200 miles per hour, the National Weather Service said on Saturday. It was part of an unusual early autumn storm system that also dropped 3 feet of snow in South Dakota and Wyoming, where a 380-mile (610-km) stretch of Interstate 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 spokesperson Jodie Fawl. "There are corn and soybean fields littered with debris all over the place from houses and buildings that were damaged," Fawl said. 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 166 to 200 mph, according to the weather service.