Blizzard paralyses north-east US and Atlantic Canada
A major snowstorm has brought swathes of the north-eastern US and eastern Canada to a standstill, leaving about half a million homes without power.
High winds and blizzard conditions have emptied the centre of Boston and Massachusetts Governor Deval Patrick has banned all non-essential traffic.
Millions of people across New England have been warned to stay indoors. The region's airports are closed.
Many areas are under two feet (60cm) of snow and more snowfalls are expected.
Blizzard warnings are in effect for much of the coastal section of the north-eastern US, from Newark, New Jersey to southern Maine.
Forecasters said the storm, which began on Friday, could dump as much as three feet in some places.
People have been warned to stock up on food and other supplies as the storm affects 25 million people in the region.
More than 600,000 homes and businesses are without power in Massachusetts, Rhode Island and Connecticut.
Boston's Financial District was deserted early on Saturday - as were many streets across the region.
"This is a storm of major proportions," warned Boston Mayor Thomas Menino. "Stay off the roads. Stay home."
Snow piled up so high in places that many residents found they could not open their doors to leave their homes on Saturday, the Associated Press news agency reports.
The town of Gorham, Maine, was buried under more than 31in (78 cm) of snow. Town council chairman Philip Gagnon told Reuters news agency that many roads would not be cleared until Sunday or Monday.
"It's going to probably take some time because they can only do so much before we can rest them," he said.
In Manhattan in New York, normally bustling streets were quiet on Saturday - apart from snow blowers.
Resident Bill Tavonallo, 39, told AP: "It's nice to have a reason to slow down."
The state-wide driving ban declared in Massachusetts is the first since 1978. A similar ban is in force in Connecticut, where Governor Dannel Malloy said: "Please stay home once the weather gets bad except in the case of real emergency."
Airlines cancelled more than 5,000 flights - including all those to and from the three major airports in New York City - and the train operator Amtrak has suspended nearly all services north of the city.
Canadians on the Atlantic Coast are also bracing for blizzards after heavy snow fell on Ontario.
New Brunswick, Nova Scotia and Newfoundland are under blizzard or storm watches.
Ontario has already seen 200 vehicle accidents, the CBC reported. At least three people have been killed.
One US man in his 70s also died when he lost control of his vehicle in Poughkeepsie, New York.
Fuel shortages were being reported from Connecticut to New York City as motorists queued at petrol stations to fill up vehicles, generators and snow blowers.
The National Weather Service had earlier said the combination of two weather systems from the polar and sub-tropical jet streams would produce a "potentially historic" storm.