WASHINGTON, April 2 (AFP) - At least 21 people have been killed and dozens more injured after storms and tornadoes tore through towns and cities across Southern and Midwestern parts of the United States.

Several tornadoes touched down on Friday night across at least eight states, laying waste to homes and businesses and splintering trees, as part of a sprawling storm system that brought wildfires to the southern plains states and blizzard conditions to the upper Midwest.

Tens of thousands lost power as the storms smothered a swath of the country home to some 85 million people.

The dead included seven in the state of Tennessee, five in neighbouring Arkansas, and four in Illinois. Other deaths were reported in the states of Indiana, Alabama and Mississippi.

In Alabama, Governor Sarah Huckabee Sanders declared a state of emergency and activated 100 members of the National Guard to help local authorities respond.

Four of the deaths in Arkansas were reported in the town of Wynne, a community of about 8,000 people. Stunned residents of the town woke on Saturday to find the high school’s roof shredded and its windows blown out. Huge trees lay on the ground, their stumps reduced to nubs. Broken walls, windows and roofs pocked homes and businesses.