(CNN) -- A father and son drowned in the basement of their home. A young girl was killed when the storm surge swallowed her house. A woman was electrocuted when she stepped on a downed electrical line.
Still others were missing: Two boys ripped from their mother's arms by fierce waves, and a man believed to have been carried away by floodwaters.
As authorities in nine states tallied the devastation brought by Superstorm Sandy and struggled to restore basic services early Thursday, the human toll mounted.
At least 56 people in the United States and one in Canada died during the storm, raising Sandy's overall death toll to 124 after earlier claiming 67 lives in the Caribbean.
It is unknown exactly how many are unaccounted for in the aftermath of the storm. There are numerous reports in New York, New Jersey and elsewhere of ongoing search efforts for people reportedly swept away or missing.
Among those killed by Sandy were 28 in New York. "Tragically, we expect that number to go up," New York Mayor Michael Bloomberg told reporters Wednesday.
The body of 13-year-old Andrea Dresch was pulled from the debris of a house in New York's Staten Island that was swallowed by a tidal surge when Sandy swept ashore, authorities told CNN affiliate WCBS on Wednesday. Her father was among those reported missing, SILive.com reported.
Sandy came ashore late Monday in southern New Jersey, wiping out houses, pushing sand four blocks inland in places and leaving thousands stranded.
Search and rescue crews were going door-to-door in some neighborhoods looking for people, particularly the elderly, stranded by the power outages, the debris and remaining floodwaters.
Sandy killed at least six people in New Jersey, said Gov. Chris Christie, who had warned people in low-lying areas to evacuate. "We're lucky that more people didn't die as a result of folks ignoring those warnings," he told reporters.
A number of deaths were caused by the storm surge, downed electrical lines and cold weather.
Lauren Abraham, 23, was killed Monday outside her Jamaica, Queens, home in New York when she stepped on a downed electrical line in a puddle, police said.
The Lehigh County, Pennsylvania, coroner attributed the death of 86-year-old Theresa Schlitzer to hypothermia after she was found unconscious in her yard, CNN affiliate WHTM in Harrisburg reported.
Schlitzer died Tuesday after spending nearly 12 hours outside in the storm, the coroner told WHTM. Details about why Schlitzer was outside and how she became incapacitated were not immediately available.
Boats were washed onto front yards in the Staten Island neighborhood of Great Kills. Borough President James Molinaro said the waters have mostly receded, but the damage is severe. Several people, including two young boys, are missing.
Among those also reported missing were two boys, ages 2 and 4, who were separated from their mother when the SUV they were riding in was overwhelmed by the storm surge that struck New York's Staten Island, authorities told CNN affiliate NY1.
The mother and two boys escaped the SUV that was quickly filling with water only to be overtaken by the storm surge.
"She had them in her arms, and a wave came and swept them out of her arms," a family member told the New York Daily News.
In the same New York City borough, John Filipowicz, 51, and his 20-year-old son John were found dead after being buried under debris in the basement of their State Island home after it was swamped by the storm surge, authorities said, police told WCBS.
Commuters, homeowners and businesses, meanwhile, struggled with the loss of power and waterlogged or burned homes.
Many are still in need of basic supplies. President Barack Obama visited a shelter Wednesday in Brigantine, New Jersey, where he said he met a woman with an 8-month-old who has run out of diapers and formula.
"Those are the kinds of basic supplies and help that we can provide," he said.
Obama promised the federal government "will not quit" until communities are cleaned up.
"We are not going to tolerate red tape, we are not going to tolerate bureaucracy," Obama said. "And I've instituted a 15-minute rule, essentially, on my team. You return everybody's phone calls in 15 minutes, whether it's the mayor's, the governor's, county officials.
"If they need something, we figure out a way to say yes."
Christie asked for patience as crews worked to turn the power back on for more than 2 million people still in the dark. He toured the hard-hit town of Brigantine on Wednesday with Obama, who said utilities from across the country have pledged to send crews to New Jersey as soon as possible.
By early Thursday, the remnants of Superstorm Sandy headed north through Canada, with the last of its effects beginning to wind down along the Appalachian Mountains, according to the National Weather Service.
The storm brought 2 to 3 feet of snow to some areas in West Virginia and Maryland, leaving thousands without power. Several more inches of snow are possible in some areas before the storm ends later this week, the weather service said.
A little less than 4.9 million customers across the eastern United States were still in the dark early Thursday, down from the nearly 8 million who lost power shortly after the storm hit.
CNN's Joe Sterling and Melissa Grey contributed to this report.