In the aftermath of the devastating tornado that struck Oklahoma on Monday, Pope Francis sent out a tweet expressing sympathy for the victims of the disaster.

“I am close to the families of all who died in the Oklahoma tornado, especially those who lost young children. Join me in praying for them.”

At least 51 people are now known to have died, including 20 children, when the massive tornado swept through the suburbs of Oklahoma City, USA. Officials, though, have said the death toll is expected to rise, as search and rescue operations continue throughout the night and into the morning.

One elementary school was destroyed and another was damaged when the half-mile wide tornado touch down. The storm was on the ground for about 45 minutes, sparking fires and flattening homes. Worst hit was Moore, south of Oklahoma City, where whole neighbourhoods were levelled by winds of up to 200mph.

It is the second day in a row the Midwestern state of Oklahoma has been slammed by twisters. About 120 people are being treated in hospitals. President Barack Obama has declared a major disaster in Oklahoma.