At least 40 people have died after tornadoes ripped through a swathe of the US Midwest and South.

Missouri bore the brunt of the twisters, which began to spawn on Friday. At least 12 people have died in that state.

Powerful winds in Texas and Kansas whipped up dust storms that resulted in vehicle pile-ups and a dozen deaths.

The extreme weather, covering an area of the country that is home to more than 100 million people, fanned nearly 150 deadly wildfires in Oklahoma. Fatalities were also recorded in Arkansas, Alabama and Mississippi.

Parts of Texas, Louisiana, Alabama, Arkansas, Tennessee, Mississippi, Georgia, Kentucky and North Carolina were under flood advisories.

More than 320,000 people across the region were without power on Sunday evening, according to tracker PowerOutageUS.

States of emergency have been declared in Arkansas, Georgia and Oklahoma.