Parts of the eastern United States have received more than two feet (71cm) of snow fall in a huge blizzard that is sweeping across the region.
Heavy snow began falling on Friday across more than 20 states, affecting some 85 million people.
New York City mayor Bill de Blasio said the storm could be one of the worst to ever hit the city. He is considering a travel ban.
At least nine people have died and emergencies declared in 10 states.
Tens of thousands of homes are without power and traffic jams lasting at least 12 hours have been reported in Kentucky and Pennsylvania.
Why do so many people die shovelling snow?
The nation’s capital, Washington, could lie under a record 30in (76cm) of snow by the time the storm passes on Sunday. At the White House, 13in (33cm) of snow fell overnight.
The heaviest snowfall recorded so far (up to 09:00 eastern time, 14:00 GMT) include:
- 28in (71cm) – Terra Alta, West Virginia
- 24in (61cm) – Philippi, West Virginia; Oakland, Maryland
- 23in (58cm) – Ridgeley, Maryland; Champion and Marklesburg, Pennsylvania
The weather system affects a huge swathe of the country, from Alabama in the south to Massachusetts in the north-east.
Mr de Blasio said New York City was now expecting up to two feet of snow, which would make it one of the five largest storms ever to hit the city.
In a press conference, he urged citizens to get off the road. “This is bad and getting worse rapidly,” his office tweeted.
In Kentucky, a 35-mile (56km) traffic jam has started to clear in the past few hours, after thousands of drivers found themselves stranded on Interstate 75 overnight by heavy snow and a number of accidents.
The Red Cross erected shelters along the highway and 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.
Further north, on the Pennsylvania Turnpike, a number of other vehicles have been stuck in snow for at least 12 hours after the road closed. One university basketball team that was stranded said they were running out of leftover pizza and getting hungry.
In other developments:
- More than 7,000 flights have been cancelled for Friday and Saturday
- More than 100,000 homes lost power in North Carolina
- Another 40,000 people are without power in New Jersey
- Nine people have been killed in car crashes in North Carolina, Virginia, Kentucky and Tennessee
- In Virginia alone, state police reported 989 car crashes
- Low-lying parts of New Jersey and New York are at risk of heavy flooding
- 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 – is closed all weekend
The US federal government closed down at noon on Friday. 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,” it warned.
The most intense parts of the snowstorm are heading north towards New York state on Saturday.
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
- Make sure you have at least three gallons (13.5 litres) of drinking water per person, per day
- Tape the windows with bubble wrap to keep the heat in
- Use your dog to measure the snowfall
How to prepare for a snowstorm
Throughout the night, people took to Twitter to post updates on snow levels and pictures under the hashtag #Snowmaggedon2016.
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.
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