A “very epic bomb cyclone” has unleashed heavy rain and snow on large areas of the US, causing widespread power outages, flooding and flight cancellations.
The storm brought blizzards, floods and a tornado across more than 25 states on Wednesday and is currently moving eastward.
The conditions contributed to the death of Colorado state patrol officer Daniel Groves, who was hit and killed by a car as he helped another driver who had slid off a road near Denver.
Head of transport in Colorado, Shoshana Lew, said the death was a “tragic reminder that people’s lives are at stake” and urged drivers to stay off the roads.
Meanwhile, drivers were left stranded in blizzard conditions in Colorado and had to be rescued by national guard troops, with about 200 vehicles stuck on a major road near Colorado Springs.
Bria McKenzie, 22, was stuck in her car for more than two hours with her family and said she did not feel safe walking to a hospital down the road.
“It was just like every second you were out there, it felt like parts of you were just freezing,” she said.
Hundreds of flights were cancelled and a wind gust was clocked at 97mph in Colorado Springs, while power outages were reported across the state.
In South Dakota, all state offices were closed on Thursday as wind, blowing snow and hazardous roads made travel treacherous.
Heavy rain caused flooding in eastern parts of South Dakota, Nebraska and Iowa.
According to a report by the National Weather Service (NWS), the Spencer Dam at the Niobrara River was “compromised”, prompting a flash flood emergency and the evacuation of residents along the river.
A post on Nebraska State Patrol’s Twitter page also revealed a bridge over the Niobrara River appeared to be “gone”.
A third of the 24,000 residents in Norfolk, Nebraska, were ordered to evacuate on Thursday.
The so-called “bomb cyclone” was caused by a sudden drop in ground-level air pressure, which prompted air to rush into the low-pressure area and rise into the atmosphere.
Greg Carbin, chief of forecast operations for the National Oceanic and Atmospheric Administration’s Weather Prediction Centre, described the weather abnormality as “like a vacuum cleaner”.
“When that much air rushes higher into the atmosphere, it causes severe weather,” he said.
“This is a very epic cyclone. We’re looking at something that will go down in the history books.”
AccuWeather says winds are gusting over 70mph in central parts of the US.
The storm will gradually weaken over the next few days, but strong winds are still expected.