Oklahoma twister that hit Moore ‘more powerful than the Hiroshima bomb’

The tornado approaches Moore on Monday (Getty Images)

The vast tornado that struck an Oklahoma suburb on Monday afternoon dwarfed even the Hiroshima atomic bomb in its destructive power, according to scientists.

The US National Weather Service said the twister was 1.3 miles wide, and cut a 17-mile-long swathe through Moore, now the only city in the world to have seen two EF-5 tornados, the most powerful category. The community of 56,000 also took a direct hit from a twister packing winds of more than 300mph in 1999.

As emergency workers continued the recovery effort, officials said the search for survivors of the devastating storm was nearing its end. The death toll was revised down from 51 to 24 after the state medical examiner said that some victims may have been mistakenly counted twice.

The dead included 10 children, seven of whom were killed when the storm ripped apart Plaza Towers Elementary School. Among those killed were seven-year-old Karinna Vargyas and her four-month-old sister Sydnee, who died at home. “We just don’t know what to do any more,” their father, Phillip Vargyas, said last night.

On Tuesday afternoon, Gary Bird, Moore’s fire chief, said he was “98 per cent sure” that there were no further victims or survivors left beneath the debris. No one had been found since Monday night.

Emergency crews reportedly struggled to navigate the storm-ravaged neighbourhoods as all the street signs had been destroyed; they were forced to use smartphones and GPS to pick their way through.

Schools, homes and hospitals were all levelled by the tornado, which is known to have injured at least 237 people. Some 100 survivors were pulled from the rubble.

This was the deadliest tornado to strike the US since 2011, when a twister ripped through Joplin, Missouri, claiming 161 lives.

The Mayor of Moore, Glenn Lewis, vowed to drive through a new law requiring stormproof shelters to be built in every new home. “We’ll try to get it passed as soon as we can,” he told CNN.

Homeland Security Secretary Janet Napolitano was due to travel to Oklahoma, while President Barack Obama will fly in on Sunday. A statement tonight said the President would “see first-hand the response to the devastating tornados, visit with impacted families, as well as thank first responders”.