Devastating tornadoes have killed more than 290 people in the southeast of the United States.
At least 195 people died in Alabama alone and officials expect the death toll to rise. A state of emergency has been declared in seven states.
President Barack Obama is travelling to Alabama for a first-hand look at the unfolding human tragedy.
Deaths and widespread devastation are also reported in Tennessee, Mississippi, Georgia and Virginia.
The BBC said the US National Weather Service has reports of nearly 300 tornadoes since the storms began last Friday, more than 150 of them on Wednesday alone.
In Alabama, as many as one million people were without power as emergency workers and 2,000 soldiers scoured the wreckage for survivors.
One Tuscaloosa resident, Angela Smith, whose neighbour was killed, told Reuters: “I made it. I got in a closet, put a pillow over my face and held on for dear life because it started sucking me up.”
The United States has more tornadoes than any other country, averaging 1,200 to 1,300 per year, said Joshua Wurman, a scientist and president of the nonprofit Centre for Severe Weather and Research in Boulder, Colorado.
More than half of tornadoes occur from April to June, when cool, dry air from Canada collides with warm, moist Gulf of Mexico air.
By Ian Jarrett
