An Iowa Department of Transportation snow plow slid off the road Monday morning. (Twitter/Iowa State Trooper Jon Stickney)

Winter Storm Jupiter killed at least seven as the dangerous system moved through the Plains and Midwest with freezing rain and accumulating ice.

Four deaths have been confirmed due to icy roadways in Missouri, while two died in Kansas and one was killed in Oklahoma. Emergency management officials said 65 people were injured in Oklahoma during the storm, and most of those injuries were falls.

Roads in the Midwest and Plains remained icy into the week, and schools were closed or delayed as crews continued working to make streets and highways safe for travel.

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Earlier last week, the storm slammed the Northwest with snow, collapsing roofs in Oregon and closing several interstates in the Rockies. Stretches of Interstates 70 and 80 were closed, and in the Rockies, additional heavy snow on top of accumulations from previous winter storms triggered avalanches that covered roads.

In Portland, Oregon, the storm dumped more than a foot of snow in places. Residents across the city ditched their cars as roads became impassable, and plows struggled to keep up with the heavy snow.