a tornado has killed at least 23 people in the us state of mississippi, in the south of the country. the authorities said the storm left a trail of damage for more than 150 kilometres. president biden has called the storms heartbreaking and vowed federal support. one of the worst affected towns is rolling fork where entire neighborhoods were flattened to rubble. our north america correspondent, david willis, reports. the extent of the devastation is truly extraordinary. entire communities reduced to piles. heavy vehicles were picked up and tossed around like toys. dozens are still missing but it s difficult to imagine anyone emerging from this sort of devastation alive. the tornado struck at night, leaving bewildered residents struggling to take and the impact of such a malevolent