Crews worked to restore electricity to thousands of customers in parts of northeastern Minnesota that were raked by winds up to 75 m.p.h. as powerful thunderstorms crossed the Midwest during the night. Winds gusting to 70 m.p.h. also blew down trees and power lines and damaged roofs across parts of southeastern South Dakota, northwestern Iowa and northeastern Nebraska and 1 to 4 inches of rain soaked the region, the National Weather Service said. Scattered tornadoes also were reported. Roofs were ripped off and trees were toppled around Duluth, Minn., the port on Lake Superior, and in adjoining Superior, Wis.