Rescuers sifted through rubble looking for more dead and wounded after two back-to-back tornadoes touched down in Alabama, US, killing at least 23 people, authorities said.
The storms inflicted their worst damage on Lee County, Alabama Sunday, destroying numerous homes and businesses.
More than 50 people were reported injured and the death toll is expected to rise.
Meanwhile, about 10 inches of snow was expected to fall in the New York City area by Monday morning with the arrival of another arctic blast, prompting all schools in the city to be closed and New Jersey to declare a state of emergency.
Punishing cold winds will make it feel 15 degrees below zero Fahrenheit in Chicago Monday with the windchill effect, the National Weather Service said. Actual temperatures will hover around 15 degrees Fahrenheit Monday.
Classes in schools across Boston were also cancelled or delayed as about 7 inches will fall by morning before turning into icy sleet, said Bob Oravec, a forecaster with the weather service.
"Winter is definitely not over," Oravec said.
COLD WEATHER WARNING
In Alabama, Lee County Sheriff Jay Jones said that rescue and recovery operations overnight were difficult.
"The challenge is the sheer volume of the debris where all the homes were located," Jones said in an interview with CNN on Sunday. "It's the most I've seen that I can recall."
On Twitter, US President Donald Trump urged residents of Alabama and other areas affected by the storms to be "careful and safe."
"Tornadoes and storms were truly violent and more could be coming," Trump wrote. "To the families and friends of the victims, and to the injured, God bless you all!"
As thousands faced a night without power, temperatures in Alabama looked set to fall to near freezing following the storm.
"Colder air will sweep into the Southeast behind the severe weather with temperatures dropping into the 30s (1 C) southward to central Georgia and across most of Alabama by Monday morning," AccuWeather meteorologist Kristina Pydynowski said.
"Those without power who rely on electric heat need to find ways to stay warm," she added.