New York Governor Andrew Cuomo declared a state of emergency Tuesday for several counties in and around Buffalo, where a severe winter storm has already covered parts of the region in over three feet of snow.

The National Guard will be deployed to the affected communities to residents dig out, according a statement on the New York State governor’s website. Forecasters are predicting the snowy conditions could last through the week.

“This storm may persist until Friday morning with the potential for another two feet of snow,” Cuomo said in the statement. “New Yorkers in these areas should exercise extreme caution, and stay off the roads until conditions are clearer and safer.”

Four people have died due to the storm so far, including three from heart attacks and one who was fatally pinned while pushing a car out of snow, ABC News’ Buffalo affiliate WKBW reported. Meanwhile, hundreds of cars remain stranded on roads as temperatures plummeted across the nation — all 50 states experienced freezing temperatures Tuesday.

Snow levels are forecasted to reach over six feet in some parts of Western New York areas, while other spots have experienced snowfall rates of 4 to 5 inches an hour. The massive snowstorm is a result of what’s called the “lake effect,” in which moisture over the Great Lakes freezes into snow and blows onto land. The lake effect also results in a strange phenomenon where areas as close as a few minutes of driving from snow-pounded towns have almost no snow at all.

The snow storm is expected to continue through at least Thursday, reaching parts of central New York, before dissipating. It may even break Buffalo’s all-time record of 82 inches of snow falling over five days in 2001, according to Buffalo News.

Read next: More Snow Expected in Buffalo’s Deadly Winter Storm

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