Fears have mounted that as many as two dozen school children may have been killed in the massive tornado that struck the suburbs of Oklahoma City.
Amid a frantic rescue effort at Plaza Towers Elementary in Moore, Oklahoma, local news station KFOR reported that there "don’t appear to be any more survivors" after seven children’s bodies had been removed.
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The report said authorities believed "20 to 30 more children may be inside, but do not believe there are any more survivors".
The fears come as Oklahoma's state medical examiner's office confirmed that 51 people had been killed in the tornado, with the death toll expected to rise. It's not immediately clear if that total would include the school children.
The tornado, with winds of up to 267 kilometres per hour, was so violent that it flattened neighbouring homes, stripping parts of Moore not only of its homes, cars, trees and shrubs, but according to some reports, even of its grass. The tornado, which measured three kilometres wide, hit in the afternoon as children were preparing to leave school.
National Guard troops and volunteers searched for survivors as the sun went down.
At least 75 students were in the the Plaza Towers Elementary school at the time, local TV station KFOR reported. As many as 30 may have been rescued, the station said. Earlier reports suggested 13 children were buried in the rubble. However, later reports indicated that the number may be higher.
"Twenty-four victims are assumed to be in the rubble of the Plaza Towers Elementary school," the KFOR news station website said.
A reporter at KFOR recounted coming across a pair of surviving children who told of seeing a badly injured teacher lying across the three children he or she had laid across to protect. Bloomberg reported that two schools have been wrecked in the destruction.
"It seems that our worst fears have happened today," Bill Bunting, a National Weather Service meteorologist in Oklahoma, said, according to Reuters.
"I have never seen anything like this in my 18 years covering tornadoes here in Oklahoma City. This is without question the most horrific," said Lance West, a reporter for KFOR.
Another reporter spoke of coming across a survivor who was looking for other family members but could not even find their home, so completely had the street scape been destroyed.
There are 13 kids that are in a school that collapsed, we don’t know whether they are alive or dead.
It was reported that an estimated 30 square miles (77 square kilometres) around the suburb of Moore, Oklahoma had been devastated. The Oklahoma Governor Mary Fallin declared 16 counties disaster areas.
Early footage of the damage showed a zone scraped bare, with flashes similar to lightning strikes flickering where electricity installations were destroyed. Later fires flickered in parts of the ruins, as structure fires burned in the path of destruction.
Two dozen tornado reports from Illinois to Oklahoma were logged by the storm centre, according to the agency's website.
The suburb of Moore was hit hard by a tornado in 1999. The storm had the highest winds ever recorded near the earth's surface. Many residents rebuilt their homes but added storm cellars that allow occupants to stay underground in the event of a tornado.