The death toll in the New York city of Buffalo has risen to 28, with thousands still without power amid a monster winter storm that has battered North America.
Across the US, at least 62 people have been confirmed dead across nine states.
In Buffalo, a state official said that military police are being brought in to help manage traffic in the city, where a driving ban remains in place.
Looting has been reported in parts of the city during the emergency.
Officials have said conditions are improving, with very little snowfall on Tuesday and slightly warmer weather on the way.
The death toll, however, is expected to rise as search efforts continue.
Earlier, Buffalo Mayor Byron Brown said that some people had been trapped for more than two days during what was “probably” the worst storm of their lifetime.
New York’s Erie County – which includes Buffalo – is among the hardest hit areas in the winter storm, which has stretched from Canada all the way to the Mexican border. More than 4,000 people in the area remain without power, down from a high of over 20,000.
Mark Poloncarz, executive of Erie County where Buffalo is located, said that 100 military police officers and additional state police were being brought in to help control traffic in the area, where conditions remained “ugly” on many local roads.
Buffalo Police Commissioner Joseph Gragmalia said that looting is “still going on”. Four people have so far been arrested.
“This isn’t people stealing food and medicine and diapers,” he said. “They’re destroying stores. They’re stealing televisions, couches, whatever else they can get their hands on. They’re opportunists.”
US President Joe Biden approved an emergency declaration on Monday allowing federal support for New York State. “My heart is with those who lost loved ones this holiday weekend,” he tweeted.
Neighbouring state New Jersey also sent emergency services to New York state to provide further assistance.
State Governor Kathy Hochul, a native of Buffalo, described the storm as “the blizzard of the century”.
“It is [like] going to a war zone, and the vehicles along the sides of the roads are shocking.”
She added that many emergency vehicles had been unable to reach worst-hit areas or had got stuck in snow themselves.
New York state officials said emergency personnel were going from car to car searching for survivors of the storm, and finding bodies in cars and snow banks.
Mr Poloncarz said others died from cardiac arrest while ploughing snow, with Buffalo state issuing a “Shovel Smart” warning, notifying people that over-exertion from shovelling snow can cause heart attacks or back injuries. While three additional deaths were confirmed by Tuesday morning, two deaths that had been reported earlier were deemed a “non-storm related”, he added.
One local family with young children – aged two to six – had to wait for 11 hours before being rescued in the early hours of Christmas Day (Sunday).
“I was basically just hopeless,” the father, Zila Santiago, told CBS News. He said he managed to stay warm by keeping the engine running, and kept distress at bay by playing games with the children.
Ditjak Ilunga from Gaithersburg, Maryland, told CBS News he was on his way to visit relatives in Hamilton, Ontario, with his daughters when their SUV was trapped in Buffalo.
After spending hours with the engine running he made the desperate choice to risk the howling storm to reach a nearby shelter.
He carried six-year-old Destiny on his back while 16-year-old Cindy clutched their Pomeranian puppy, and followed his footprints in the snow drifts.
“If I stay in this car I’m going to die here with my kids,” Mr Ilunga recalled thinking.
He said he cried when the family walked through the shelter doors. “It’s something I will never forget in my life,” he said.
Meanwhile, the owner of a small family-run shop in East Buffalo, who didn’t want to be named, said looters broke into his general store on Christmas Day.
“They took everything. People took toys, electronics and speakers,” he said.
He estimated up to $50,000 (£41,000) worth of equipment was stolen. He said he called the police, “but they told me they were too busy rescuing the elderly”.
Mr Poloncarz said: “We can see sort of the light at the end of the tunnel, but this is not the end yet.”
“It’s a generational storm,” he added.
The “bomb cyclone” winter storm – which occurs when atmospheric pressure plummets, causing heavy snow and winds – has disrupted travel across the US.
Nearly 4,000 US flights were cancelled on Monday, according to tracking site Flightaware.com. An additional 4,600 flights were cancelled by mid-morning eastern time on Tuesday.
Forecasters say bad weather will ease in the next few days, but the advice remains to avoid travelling.
Over the weekend an estimated 250,000 homes and businesses experienced blackouts – although power has been steadily restored.
Storm-related deaths were also reported in Vermont, Ohio, Missouri, Wisconsin, Kansas, and Colorado. South Florida’s temperatures dropped so low, that iguanas froze and fell from trees.
The western US state of Montana was the worst hit by the cold, with temperatures dropping to -50F (-45C).
In Canada, the central province of Ontario and Quebec, in the north-east, bore the brunt of the storm.
Ontario’s Prince Edward County, along Lake Ontario, declared a state of emergency and had to take snow ploughs off the streets because they were in danger of getting stuck, Mayor Steve Ferguson told CBC News.
Four fatalities earlier occurred when a bus rolled over on an icy road near the town of Merritt, in the western province of British Columbia.
