Oklahoma tornado: Dozens killed in Moore

At least 91 people, including 20 children, have been left dead after a huge tornado tore through Oklahoma City suburbs, officials in the US state say.

Worst hit was Moore, south of the city, where neighbourhoods were flattened and schools destroyed by winds of up to 200mph (320km/h).

About 120 people are being treated in hospitals.

President Barack Obama has declared a major disaster in Oklahoma.

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 at least 20 children were among the 91 dead.

Plaza Towers Elementary school took a direct hit: the storm tore off the building's roof and knocked down walls, BBC reports.

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