A huge winter storm sweeping across the southern US has killed at least 21 people and left millions without power.
There have been widespread blackouts in Texas, where the energy grid was overwhelmed by a surge in demand.
Millions of people in the state, which rarely experiences such low temperatures, have been struggling to cope with the lack of power and frigid conditions.
The extreme weather is forecast to continue until the weekend.
Deaths attributed to the storm have been recorded in Texas, Louisiana, Kentucky, North Carolina and Missouri.
The National Weather Service (NWS) said more than 150 million Americans were now under winter storm warnings.
And on Tuesday, it reported that more than 73% of the US was covered by snow.
The freezing storm has even reached northern and central parts of Mexico, where millions of people have experienced days of intermittent power cuts.
“I’m in Houston, Texas freezing to death,” one Twitter user, Chris Prince, wrote. “No power, no heat, no water. I have four young children. How is this happening right now?”
Another user, Josh Morgerman, wrote that a friend in Texas had resorted to “burning furniture in the fireplace” to stay warm.
The recorded deaths include people who have died in traffic accidents, as well as some who suffered carbon monoxide poisoning from running cars and generators indoors to stay warm.
“This is an absolute public health disaster,” one medical official in Houston told the local television station KPRC-TV. “[Carbon monoxide poisoning] certainly happens when it gets cold, but never in these numbers.
One county said it had seen more than 300 suspected carbon monoxide cases during the cold snap. “It’s turning into a mini mass casualty event,” one Harris County doctor told the Houston Chronicle.
At least four people were killed following a house fire in Houston that officials said may have been sparked by candles. Separately, police said two men found alongside a Houston highway were believed to have died due to the cold.