Tornadoes kill hundreds in southern USA

President Obama has declared a state of emergency in Alabama after the death toll there alone rose to 131. A further 32 have been declared dead in Mississippi, 10 in Georgia and 11 in Arkansas, with deaths also reported in Arkansas, Louisiana and Tennessee.

In all more than 220 are believed to have lost their lives to the storms, with an estimated one million people affected by power cuts.

As the intense wind and rain showers continue, concerns are now shifting towards the risk of extreme flooding.

Authorities in Alabama and Mississippi have said they expect the death toll to rise as the rescue operation continues. 137 tornadoes have been reported across the affected states, with 66 of those in Alabama. President Obama is to travel to the state to view the damage on Friday.

One expert tells Channel 4 News: "The Alabama tornadoes seem to be about as big as tornadoes can get." Read more: What causes tornadoes?

One tornado, measured at a mile in width, ripped through the university town of Tuscaloosa. One resident explained how they were forced to take shelter in the basement of their home: “We could hear debris hitting the side of our house, glass breaking and the train sound often attributed to big storms such as these.”

Alabama Governor Robert Bentley admitted that some of the dead in Tuscaloosa were students who lived off campus. He told a news conference in Monterey: “There are very few times in my lifetime and in your lifetime that you can remember an outbreak of tornadoes, long-track tornadoes like we’re having right now at this present time.”

On the White House blog, President Obama, who had earlier pledged federal aid to the areas hit, said: “Our hearts go out to all those who have been affected by this devastation (…) and (we) stand ready to continue to help the people of Alabama.”

Incredible footage shows the speed and ferocity of the tornado and video of the damage caused shows the sheer devastating effect the storms are having across the deep south to buildings, homes and cars.