More than 4 million people across five states were under winter storm alerts on Sunday as heavy lake-effect snow continued to bury the Great Lakes region, prompting emergency declarations and the deployment of National Guard troops to rescue stranded motorists.

Lake-effect snow buried northern parts of the U.S. over the Thanksgiving weekend, bringing below-freezing temperatures. Several inches of snow fell in western and northern New York, prompting a state of emergency to be declared in several counties.