Chicago: A brutal cold wave moved eastward Thursday after bringing temperatures in the US Midwest lower than those in Antarctica, grounding flights, closing schools and businesses and raising fears of hypothermia.

The extreme weather has now been blamed for as many as eight deaths, US news outlets reported. Mail deliveries were suspended and people were encouraged to stay home in nearly a dozen US states where the mercury plunged into the negative double digits, the worst freeze to grip the region in a generation.