Monster Tornado Tears Through Oklahoma City

A massive tornado has torn through Oklahoma City, killing at least 37 people and destroying everything in its path.

The tornado flattened entire neighbourhoods in the southern suburb of Moore with winds of up to 200 mph, leaving buildings on fire and landing a direct blow to an elementary school.

Several children were pulled alive from the wreckage of Plaza Towers Elementary School after the devastating, mile-wide tornado reduced the building to heaps of rubble and twisted metal.

Rescuers were passing the rescued children down a "human chain" to get them to medical personnel for treatment.

Roughly 500 students attend the school in the suburban town of Moore. It is unclear whether any had been evacuated before the twister hit, but local media is reporting some children were taken to a nearby church.

Firefighters were at the scene digging through the school's debris to reach any children possibly trapped inside.

The Oklahoma Medical Examiner's Office confirmed 37 people had been killed. It is unknown how many of these were children.

Officials at two hospitals said they were treating nearly 60 patients, including more than a dozen children. At least 10 people were said to be in a critical condition.

President Barack Obama said a federal emergency rescue team was working with authorities in the area.

Oklahoma Governor Mary Fallin said: "This is a very sad day for the state of Oklahoma - a very hard day and very tragic day.

"Our prayers and our thoughts are with all the Oklahoma families that have been hit hard by this terrible storm.

"We are doing every single thing that we can to assist those that are in need right now."

She said she had deployed 80 Oklahoma National Guard members to assist search and rescue teams who were "looking under every single piece of debris" to find anyone that might be injured or lost.

The National Weather Service has given the twister a preliminary EF-4 classification - on a five-point scale - with winds up to 200mph. 

Weather service meteorologist Kelsey Angle said fewer than 1% of all tornadoes ever reach EF-4 or EF-5 levels.

Moore's hospital was badly damaged, and there were also unconfirmed reports that a second school was destroyed.

Several other tornado warnings were also in effect following the devastating twister.

Monday's mid-day twister came just a day after two people were confirmed killed by a tornado nearby.

Residents of Moore had been urged to take shelter as the violent storm moved through the area.

The broad, dark funnel cloud was on the ground for 35 minutes before dissipating.

KFOR-TV's news helicopter showed huge swaths of buildings and homes completely levelled, with nothing but wreckage left. Some homes were taken down to their concrete slabs.

Sky News US Correspondent Dominic Waghorn described the damage, saying "whole neighbourhoods just wiped off the map, homes literally stripped to their foundations".

Aerial footage showed vehicles crumpled and overturned in piles of debris on the motorway, and buildings that were unrecognisable jumbles of rubble.

Emergency personnel and volunteers had begun going door-to-door searching for victims.

Utility workers were in an urgent rush to shut off electricity and gas to the area to prevent further danger from live power lines or natural gas leaks.

Footage of the storm shows the monster twister slowly moving through the area and the flashes of power lines blowing.

The Oklahoma National Guard was deployed after the storm to help begin the recovery effort.

The huge tornado was the most recent in a series of twisters that has ravaged towns in the midwest US in recent days as a line of violent storms has stretched from the Canadian border down into Texas.

This part of the country is known as "tornado alley" and residents are trained in how to take shelter. Most towns and cities are equipped with storm sirens that can warn of a coming tornado a half hour before it hits.