A massive blizzard bringing more than 2ft (60cm) of snow and punishing winds is advancing up the US East Coast.
More than 50 million people across more than a dozen states have been warned to stay at home as it moves north.
The nation's capital, Washington, could lie under a record 30in (76cm) of snow by the time the storm passes on Sunday.
At least nine people have been killed and a state of emergency declared in 10 states. Transport services have been cancelled, and homes are without power.
The weather system affects a huge swathe of the country, from Arkansas in the south to Massachusetts in the north-east.
Supermarkets ran out of food amid a rush for supplies before the first snowflakes fell on Friday.
- By early Saturday, more than 18 inches (45cm) of snow had fallen in parts of Kentucky and seven inches had fallen in Washington, the National Weather Service reported
- More than 7,000 flights have been cancelled for Friday and Saturday
- More than 100,000 homes lost power in North Carolina
- Nine people have been killed in car crashes in North Carolina, Virginia, Kentucky and Tennessee
- In Virginia alone, state police had reported 989 car crashes by Friday evening
- States of emergency have been declared in Tennessee, Georgia, Kentucky, North Carolina, New Jersey, Virginia, West Virginia, Maryland, Pennsylvania, the District of Columbia
- Washington's transport system - the second busiest in the US - will close all weekend
- Many events, including two sold-out concerts by singer Garth Brooks in Baltimore, have been postponed
The US federal government closed down at noon on Friday as Washington's mayor, Muriel Bowser, warned this was a major storm with "life and death implications". President Obama is remaining at the White House.
The National Weather Service (NWS) warned that the worst of the snow would fall in the Washington area from the early hours of Saturday to the early afternoon, with winds of more than 50mph (80kph).
In a warning at 02:17 (07:17 GMT), the NWS tweeted that an "intense snow band" was moving through the area, "expect rapid accumulations and near-whiteout conditions".
Residents in the capital and surrounding suburbs in Virginia and Maryland have been warned the snowfall could eclipse the district's record of 28in that fell during a two-day period in 1922.
The BBC's Laura Bicker, in Washington DC, says it feels as though the city is in hiding - the streets are empty and restaurants, bars and supermarkets remain closed.
Residents have been told to find a safe place and stay there until the storm has passed.
Some tips on surviving a snowstorm:
1.Make sure you have at least three gallons of drinking water per person, per day
2.Tape the windows with bubble wrap to keep the heat in
3.Use your dog to measure the snowfall
Throughout the night, people were taking to Twitter to post updates on snow levels and pictures under the hashtag #Snowmaggedon2016.
In Kentucky, the Red Cross erected shelters along Interstate 75 for the more than 3,000 people who became stranded after multiple crashes forced the closure of the highway.
Kentucky State Police tweeted that officers were taking water, fuel and snacks to the motorists, some of whom had been stuck for more than 12 hours.
Local TV reporter Caitlin Centner was one of those stranded. She told her station WKYT-TV: "Every time it looks like there's light at the end of the tunnel, more accidents and slide-offs are occurring."
In Baltimore, teams of mental health specialists were working to bring some of the estimated 3,000 homeless people to shelter, the New York Times reported.
Supermarket shelves in many areas were bare. In Baltimore, shopper Sharon Brewington remembered how she and her daughter were left with just noodles and water when the last big snowstorm struck in 2010.
"I'm not going to make that mistake again," she said.