At least nine people have died, more than 1,000 flights have been cancelled and hundreds of thousands are without power in seven US states as a massive winter storm system dumped snow, freezing rain and hail.
Hurricane-force wind gusts, golf-ball-sized hail and five to 13 centimetres of snow fell on Friday night and early Saturday as storms pushed from Texas through the southeast and Great Lakes into Maine.
More snow was expected through Sunday in parts of Illinois, Michigan, northern New York and New England, the National Weather Service said.
"The real danger comes from the wind and ice accumulation," NWS forecaster Bob Oravec said.
More than one centimetre of ice was predicted to cake highways and roads across the south and northeast from Saturday night to Sunday morning, he said.
"The ice and wind will make driving treacherous, and trees can snap and knock out power and do other damage," he warned.
Two people were killed when the storm destroyed a trailer home in northwest Louisiana late on Friday, according to the Bossier Parish Sheriff's Office.
Local media reported that a third person died after a tree fell on a home in that state.
A fourth person was killed on Friday when a car slid off the road and into a creek in Dallas, NBC news reported.
People clean up the classrooms of Benton Middle School in Benton, Louisiana. Source: The Shreveport Times
A firefighter and a police officer in Lubbock, Texas, were killed on Saturday after a car slid on an ice-slicked highway as they were investigating a traffic accident, Lubbock Fire officials said.
And three more storm-related deaths occurred in Pickens County in western Alabama, CNN reported, but details were not immediately available.
About 200,000 homes and businesses were without power across Texas, Louisiana, Mississippi, Arkansas, Tennessee, Illinois and Michigan, according to the tracking site PowerOutage.us.
The bulk of the nation's flight delays and cancellations were at Chicago's O'Hare International Airport, with more than 1000 flights cancelled and hundreds more delayed, according to flightaware.com.
Tornadoes damaged or destroyed some buildings in Arkansas and Missouri, forecasters said.
A family member of a south Bossier, Louisiana, couple killed in overnight storms searches through the remains of their home. Source: The Shreveport Times
The NWS said more than 18 million people in Louisiana, Arkansas, Texas and Oklahoma remained at risk of tornadoes and flooding rains.
Oravec said hurricane-force wind gusts of about 120km/h hit the southeast.
As the system pushes eastward, rain should end overnight in many southern states, but the northeast and New England can expect severe weather to last for another day.
