An ice storm sweeping the central United States has left at least 15 people dead amid warnings of more freezing weather to come.
Most of those who died lost their lives in road accidents
More than 600,000 homes and businesses were left without electricity after icy winds toppled power lines and trees.
Forecasters have issued winter storm warnings for parts of Missouri, Kansas, Nebraska, Iowa, Illinois and Texas.
Ice up to 1in (2.5cm) thick coated parts of Oklahoma and Missouri, where states of emergency have been declared.
"The predictions were pretty grim and they're still not good at all," said meteorologist Noelle Runyan.
The worst-hit states so far have been Oklahoma and Missouri, where at least 13 people have died on roads made treacherous by driving sleet and ice.
Twelve people were killed in road accidents in Oklahoma over the weekend, including four who died in an 11-vehicle pile-up on the ice-covered Interstate 40, west of Okemah.
A highway accident claimed another life in Missouri, while a homeless man died of hypothermia in Oklahoma City.
Ice storm warning - freezing rain produces significant, and possibly damaging, accumulation of ice
Winter storm warning - storm producing, or is forecast to produce, heavy snow or significant ice accumulations
Blizzard warning - sustained wind or frequent gusts to 35 mph (56 km/h) or greater, considerable falling and/or blowing snow
US National Weather Service
News agencies said at least one other person died, but it was not clear where.
The governor of Missouri, Matt Blunt, warned: "We are only just beginning to see the devastation from this series of storms."
Flights were grounded at Tulsa International Airport, while hundreds more flights were cancelled at major air hubs in Chicago, Kansas City, St Louis and Oklahoma City.
Electricity companies in Oklahoma said that some half a million customers were without power after lines snapped under the weight of ice and falling trees.
"This is a big one. We've got a massive situation here and it's probably going to be a week to 10 days before we get power on to everybody," Ed Bettinger, a spokesman for Public Service Company, told the Associated Press news agency.
More than 100,000 people in Missouri also lost power, with several thousand others in Illinois and Kansas also suffering blackouts.