At least 11 people have been killed and hundreds of thousands of homes hit by power cuts as storms sweep across parts of the US south and east, bringing snow, hail and hurricane-force winds.
More than 1,000 flights have been cancelled as unrelenting rain and gales lash seven states along the east of the country from Texas.
Forecasters warned more than 18 million people remained at risk of tornadoes and flooding, and more snow was on its way.
Golfball-sized hail and up to 5ins of snow fell on Friday night and early Saturday as the storms pushed through the southeast and Great Lakes into Maine, the National Weather Service (NWS) said.
Firefighters found the bodies of an elderly couple near their demolished trailer in Bossier Parish, Louisiana. Their home had been carried 200ft from its foundations amid 135mph winds.
The Alabama Emergency Management Agency said that an “embedded tornado within a long line of intense thunderstorms” caused the deaths of three people.
A 75-year-old man in Oil City, Pennsylvania, was in bed when a tree fell on his home, crushing him to death, authorities said.
“The real danger comes from the wind and ice accumulation,” warned NWS forecaster Bob Oravec.
More than half an inch of ice was predicted to cake highways and roads in the coming hours, he added.
“The ice and wind will make driving treacherous, and trees can snap and knock out power and do other damage.”
Widespread downed trees and power lines caused travel disruption.
A firefighter and a police officer in Lubbock, Texas, were killed after a car slid on an icy highway as they were investigating an accident.
At Chicago’s O’Hare International Airport, about 1,000 flights were cancelled and hundreds more delayed, according to flightaware.com.
Many streams already are at or near flood levels because of earlier storms, and more heavy rain could lead to flash flooding, forecasters said.
Parts of Arkansas, Tennessee, Mississippi, Missouri, Illinois and Indiana were under flash flood warnings on Saturday.
Lightning was suspected of being the cause of two house fires in north Texas, and tornadoes damaged or destroyed homes and other buildings in Arkansas, Missouri and Oklahoma, but no injuries were reported.