Tuscaloosa (US): Shocked Americans struggled to grasp the scale of one of the worst tornados in decades which claimed at least 305 lives.

Communities like Alabama Governor Robert Bentley’s home town of Tuscaloosa were virtually wiped off the map, and officials warned the body-count would rise as rescuers uncovered more dead in the debris.

Disbelief was written on faces across eight states crippled by the ferocious spring storms -- the deadliest tornado tragedy to strike the United States since 310 people were killed on April 3, 1974.

Recalling the more recent horror of 2005’s Hurricane Katrina, families picked through the remains of homes, businesses and schools, bearing witness to scenes of devastation more common in war zones or after earthquakes.

In Alabama alone the toll reached 204, with more than 1,700 injured. President Barack Obama and the First Lady were to travel to the worst-hit state today for a first-hand look at a still unfolding human tragedy.

“The loss of life has been heartbreaking, especially in Alabama,” Obama said at the White House, describing the disaster as “nothing short of catastrophic.”

The storms “took mothers and fathers, sons and daughters, friends and neighbors -- even entire communities,” he said, vowing to rush federal assistance to those in need.

States of emergency were declared from central Oklahoma to Georgia on the eastern seaboard, and governors called out the National Guard -- including 2,000 troops in Alabama – to help with the rescue and clean-up operations.

“We had a major catastrophic event here in Alabama with the outbreak of numerous long-track tornadoes,” said Governor Bentley, who declared a major disaster for the state, where up to a million people were left without power.

As the long day dragged on, rescue workers battled to find missing people and to try to rescue survivors still trapped in the debris of their homes.

Many homes looked like they had been blown inside out, with the walls down and furniture spilling into the street.

In a parking lot at the University of Alabama in Tuscaloosa -- where 36 people were confirmed dead – tornadoes left behind 20 smashed cars, many of them piled on top of each other.

“I don't want to think now in how much I lost,” resident Robert Mitton told reporters. “I hope we can get some help from the government. I live very close, my house is much damaged, but my family is fine.”

Owen Simmons, who works in a furniture store, pointed to a black cross and a zero below painted on the side of his house.

(Agencies)