Repair crews worked to restore power to nearly half a million customers who faced a cold and dark Christmas in parts of northeastern United States and eastern Canada after a weekend ice storm.
At least 24 deaths have been linked to the storm, some from carbon monoxide poisoning as people struggle to stay warm.
In Canada, five people were reported dead from apparent carbon monoxide poisoning. Police said two people in Ontario died after using a gas generator to heat their blacked-out home northeast of Toronto.
Police in Quebec said carbon monoxide poisoning was believed to be the cause of three deaths in a chalet on the province's North Shore. Earlier, five people were killed in eastern Canada in highway crashes blamed on severe weather conditions.
In the US, the nationwide death toll from the storm reached at least 14 on Tuesday, when a 50-year-old man in Maine was overcome by carbon monoxide fumes from a generator. It was the second reported death attributed to fumes from a generator during the storm.
As temperatures plunged into the low single digits (below minus 15 Celsius) in Toronto - where about 70,000 customers remained without power Christmas morning - authorities reported a dramatic jump in calls for suspected carbon monoxide poisoning, responding to 110 calls in a 24-hour period. Officials said they typically see 20 such calls a day.
"I understand they want to keep warm, but you cannot do this. This is deadly," Toronto mayor Rob Ford said on Tuesday as the city issued an extreme cold weather alert.
Fire officials warned residents not to use any appliance that burns inside a home, and even cautioned against using a lot of candles.
Elsewhere in Ontario, about 44,000 customers were still without power early Wednesday. In Quebec, some 28,000 customers remained without power. In New Brunswick, just under 29,000 customers were still in the dark.
Canadian utility officials warned that some customers could be without power until Saturday.
The number of customers in Maine without power had dropped to 70,000 by Wednesday morning. In Michigan, about 129,000 remained without power.