The death toll from a series of devastating tornadoes that struck the United States this week has climbed to at least 291 and is likely to rise further, according to officials, given that many of those missing are still not accounted for.

As the black, funnel-shaped storms wreaked havoc across a number of states on Wednesday, including Alabama, Georgia, Mississippi, Kentucky and Tennessee, thousands were injured and left homeless and more than a million people were without power even on Friday. The U.S. Federal Emergency Management Agency (FEMA) swung into top gear immediately and President Barack Obama has promised a strong federal response.

In a statement he said, “Michelle and I extend our deepest condolences to the families of those who lost their lives because of the tornadoes that have swept through Alabama and the south-eastern U.S. Our hearts go out to all those who have been affected by this devastation, and we commend the heroic efforts of those who have been working tirelessly to respond to this disaster.”

Mr. Obama, who is scheduled to travel to one of the worst hit areas, in Tuscaloosa, Alabama, said that he had spoken with Alabama Governor Robert Bentley and quickly approved his request for emergency federal assistance, including search and rescue assets.

“While we may not know the extent of the damage for days, we will continue to monitor these severe storms across the country and stand ready to continue to help the people of Alabama and all citizens affected by these storms,” Mr. Obama said.

The storms were said to be the worst in U.S. history since 1974, when tornadoes killed 315 people. This week the death toll in Tuscaloosa alone was 36, while 33 people were reported killed in Tennessee, 33 also in Mississippi, 15 people in Georgia, five in Virginia and one in Kentucky, according to media sources.

One volunteer search and rescue worker, Israel Partridge, was quoted as saying, “It looks like something just washed parts of the town off the map... Whole subdivisions, where there were 20 or 30 houses, there is nothing left. It is just totally gone.”

Underscoring the unanticipated intensity of the tornadoes Susan Cobb, a spokeswoman for the National Oceanic and Atmospheric Administration, said, “This happens so rarely, we do not really have a context for it. This many tornadoes on such a wide scale is overwhelming.”

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