The massive snow storm that slammed the upper Midwest has been blamed for at least 16 deaths -- and it's not over yet.

The slow-moving system has been crawling across Minnesota and Wisconsin, where it dumped nearly 2 feet of snow before moving on to Michigan and Indiana.

On Monday, more than 100 vehicles were stuck on snow-covered highways in Indiana. By Monday night, all of the motorists had been rescued.

"It was a whiteout. It was like a tornado of snow," driver Kate Ergang said.

"I'm still stuck because you can't go east, west, north, south. Even though I can move, I can't go any where," said Joe Wurl, a truck driver.

Bone-chilling arctic air has swept in behind the storm. The storm continued its trek northeast early Tuesday over the Great Lakes and into Canada. More snow was possible for parts of Ohio, Pennsylvania and New York on Tuesday.

The frigid weather has also threatened crops across the South, where hard freeze warnings were in effect overnight in several states.