In pictures: Monster tornado hits Oklahoma

An aerial view of destroyed houses and buildings after a powerful tornado ripped through the area on 21 May 2013 in Moore, Oklahoma.

The huge tornado ripped through Moore - a suburb of 55,000 people.

Aerial photo shows the remains of homes hit by a massive tornado in a suburb of Oklahoma City

Entire neighbourhoods were flattened.

Tornado-devastated home on May 21, 2013 in Moore, Oklahoma.

Residents are returning to what remains of their homes. Here, a man salvages possessions from his grandmother's house in Moore.

A woman searches for possessions at sunset after the suburb of Moore, Oklahoma was left devastated by a tornado, 21 May 2013

The high winds - some of the strongest recorded - stripped vegetation from the landscape.

Derick Brock from Mercy Chefs distributes hot food to tornado victims at their devastated neighbourhood 21 May, 2013 in Moore, Oklahoma.

Residents have been helping one another cope with the aftermath of the tornado.

Overturned cars in Oklahoma following the huge tornado that struck on Monday, 21 May 2013

Many vehicles were overturned and crushed by the storm.

An aerial view of damage at Plaza Towers Elementary School in Moore, Oklahoma, 21 May 2013.

Plaza Towers Elementary School was one of the most heavily damaged buildings.

A boy is pulled from the wreckage of Plaza Towers Elementary School in Moore

Rescuers pulled a number of children alive from the wreckage of school.

Rescue workers dig through the rubble of a collapsed wall at the Plaza Towers Elementary School in Moore

But across the suburb at least nine children were among the 24 killed.

A woman carries a child through a field near the collapsed Plaza Towers Elementary School in Moore

Some pupils were carried away by their distraught parents and others.

A woman is pulled out from under tornado debris at the Plaza Towers School

President Barack Obama declared a major disaster and ordered federal authorities to join in the search efforts.

The tornado above Moore

It was at least the third tornado to strike Moore since 1999, when more than 40 people were killed.

The Moore Medical Center

The Moore Medical Center was also badly damaged by the tornado.

Rescue workers carry a woman to safety from the Moore Medical Center

Rescue workers helped free at least 15 people trapped in the debris from the building.

Flattened homes in Moore

Meteorologists said the twister generated winds of up to 200mph (321km/h) which reduced some districts to rubble.

Teachers carry children away from Briarwood Elementary school in south Oklahoma City

Teachers evacuated pupils from another school - Briarwood Elementary - which was also hit by the twister.

Dana Ulepich searches inside a room left standing at the back of her house

Here Dana Ulepich searches inside a room left standing at the back of her house.

Rachel Hilton holds stray kittens found in the debris

Rachel Hilton holds stray kittens she found in the debris of her parent's home.

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