The snowstorm currently lashing the Gulf Coast is being described as a once in a generation weather event, the National Weather Service said Monday.

A rare winter storm churned across the U.S. Gulf Coast on Tuesday, breaking snowfall records more than a century old in a southern region where flurries are unusual, as much of the United States remained in a dangerous deep freeze.

Around 40 million people, primarily across the southern US, were under some type of weather hazard, March Chenard, a meteorologist with the NWS, told BBC's partner CBS News. Another 170 million people from the Rockies to points eastward were under an extreme weather warning or cold weather advisory.