Officials worked Thursday to restore electricity and clear highways after a powerful spring snowstorm swept through the northwestern Plains, leaving four people dead and snow drifts of up to 5 feet in some areas.

The heaviest snow was reported in far western South Dakota near the Wyoming border, where the National Weather Service reported snow that was 44 inches deep in the city of Lead.

Crews struggling with the weight and volume of snow also had to find a place to put it after scooping it up, said Pat Milos, Lead's city administrator.

"There's nowhere to put it when there is this much of it," Milos said.

More than 4,000 customers remained without power Wednesday night in South Dakota's Black Hills, officials said. Some customers in North Dakota could be without electricity until Friday, according to the Mountrail-Williams County Electric Cooperative.

A stretch of about 95 miles of Interstate 90 remained shut down from Gillette, Wyo., to Spearfish, S.D. I-90 had icy pavement, zero visibility and trucks blocking parts of the road, said South Dakota Highway Patrol Capt. Greg Ingemunson.

North Dakota ranchers in the middle of calving season worked long hours to help their calves survive the storm.

"I guess we're happy for the moisture, but we're a little nervous about our new calves," Faye Burke said from her farm in the western part of the state.

Three people died Tuesday in a crash on an icy North Dakota highway amid blowing sleet and snow, state police said. Paul Woods, 44, and his children, Jesse, 11, and Millie, 10, were in a U-Haul truck that was hit head-on by a semitrailer that drifted into the wrong lane, authorities said.

A utility worker died Tuesday night in an apparent weather-related accident in northwestern North Dakota, said Bill Schell, general manager of Medicine Lake, Mont.-based Sheridan Electric Co-op.

Wind gusting to 84 mph overturned a mobile home in the Nebraska Panhandle, and gusts to 71 mph were reported in eastern Montana, officials said.

Spring storms with heavy snow are not unusual in North Dakota, said weather service meteorologist Jim Fors in Bismarck.

"We don't get them every year, but every five to 10 years, we usually get a big dump," Fors said.