More than 60 million Americans from Colorado to New England are facing ice and snow Monday in a winter storm that has already caused havoc on roads, causing multiple deaths in weather-related accidents.

As many as nine people were killed in traffic accidents in two states that may have been weather-related, authorities said.

The storm was dropping snow and freezing rain from the Rockies to the Midwest, the National Weather Service said, while strong to severe thunderstorms, possible tornadoes, and hail are now expected in the Deep South on Monday.

About 13 million people from Colorado to Connecticut were under winter storm warnings and weather advisories Sunday night, and the system expanded, stretching almost 2,000 miles, with a somewhat unpredictable track Monday, according to the weather service.

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In Nebraska, three people died and four others were injured in a crash on Interstate 80 between Omaha and Lincoln, authorities said. One of those injured remained in critical condition. The cause of the crash was under investigation, but a spokesman said that it was snowing at the time and that weather may have played a role.

I-80, the main artery through the state, was closed for much of the afternoon.

In Sarpy County, south of Omaha, another crash killed two people, Cody Thomas, a spokesman for the State Patrol, said. The cause was unclear, but the Omaha World-Herald reported that two vehicles collided underneath a bridge.

In Missouri, state troopers said they had responded to hundreds of reports of stranded motorists and dozens of crashes with injuries. Missouri State Highway Police said the state saw four weather-related fatalities on its roads, 53 injury crashes, and 525 calls from stranded motorists.

I-70 westbound near milepost 316 is BLOCKED in Riley county.



A five vehicle crash involving three semis are involved. #KSwx #StayHome pic.twitter.com/61ndK7SR9k — Trooper Ben (@TrooperBenKHP) December 15, 2019

In Utah, a 45-year-old man from Salt Lake City died after being buried in a back-country avalanche, the Summit County Sheriff's Office announced. The man was snowboarding at the time and accidentally triggered the wave of snow, according to the Utah Avalanche Center.

In Kansas, a state trooper tweeted a mile marker location and a photo showing a large truck blocking Interstate 70.

"A five vehicle crash involving three semis are involved," he wrote.

The trooper added a hashtag: "#StayHome."