Eleven people have died in winter storms in the US over the weekend, including four who died in a pile-up that involved a truck.

One man died of hypothermia.

The confirmed deaths were all in the state of Oklahoma.

The ice storm left about 400,000 people without power in central US states as temperatures plunged.

Conditions are expected to worsen, as the National Weather Service predicts up to 2.5cm of ice accumulation as a cold air mass stalls over the region.

Hundreds of flights were cancelled at major airports and parts of highways were closed.