Oklahoma tornado: 'Our hearts are broken', says governor

At least 24 people are confirmed dead, including seven children, and many are missing after a tornado tore through Oklahoma City, US officials say.

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

Several children are believed to have been killed when Plaza Towers Elementary school took a direct hit. The storm tore off the building's roof and knocked down walls.

President Barack Obama has declared a major disaster in Oklahoma.