Oklahoma City - At least 51 people have been killed after a huge tornado tore through Oklahoma City suburbs, with the death toll likely to rise.

Worst hit was Moore, south of the city, where neighbourhoods were flattened and schools were destroyed by winds of up to 200mph (321km/h).

About 120 people, including 70 children, are being treated in hospitals for their injuries.

Search and rescue efforts are continuing throughout the night.

Monday's twister hit Moore, a suburb of about 55,000 people, and remained on the ground for about 45 minutes.

The Oklahoma chief medical examiner's office said children were among the 51 dead.

At least two schools were devastated by the high winds, and there are reports that children are still unaccounted for.

Oklahoma Governor Mary Fallin said it was a "tragic" day, and that President Barack Obama had called her to offer assistance.

More than 200 Oklahoma National Guardsmen as well as out-of-state personnel have been called in to assist the search-and-rescue effort.

'Devastating'

Shocked survivors spoke of the tornado's power.

"We locked the cellar door once we saw it coming, it got louder and next thing you know is you see the latch coming undone," survivor Ricky Stover said.

"We couldn't reach for it and it ripped open the door and just glass and debris started slamming on us and we thought we were dead, to be honest."

BBC