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.

Here's everything you need to know about the lake effect snow that affected Sunday night's Bills vs. 49ers game.

In Erie County, Ohio, a lake-effect snow warning is in place until 7 p.m. on Tuesday. Between 10 and 20 inches of heavy snow accumulations are expected in the north of the county, while between 12 and 24 inches are expected in the south.