A frigid winter storm has killed at least 22 people as it swept across the United States, knocking out power to hundreds of thousands of homes and businesses and leaving millions of people on edge about the possibility of Christmas Eve blackouts, CNN reported.

More than 200 million people were under an advisory or warning on Friday, the National Weather Service said. The weather service's map "depicts one of the greatest extents of winter weather warnings and advisories ever," forecasters said.

Based on the latest report, the storm is still pummeling parts of the upper midwestern and interior northeastern areas in U.S. with heavy snow and blizzard conditions. 

Areas including Minnesota, Iowa, Wisconsin, Michigan and Buffalo, New York are reportedly seeing nearly white-out conditions, according to the U.S. National Weather Service. The situation is also severe in Canada's Ontario and Quebec as the storm brought power cuts to hundreds of thousands.