Overturned cars are seen after a huge tornado touched down in the town of Moore, near Oklahoma City, Oklahoma May 20, 2013. [Photo/Agencies]

MOORE, Oklahoma - A monstrous tornado as much as a mile (1.6 kilometers) wide roared through the Oklahoma City suburbs, killing at least 37, flattening entire neighborhoods with winds up to 200 mph (320 kilometers) and landing a direct blow on at least one school.

An Oklahoma Medical Examiner's Office spokeswoman said the death toll was expected to rise. Officials at two hospitals said they're treating nearly 60 patients, including more than a dozen children. At least 10 people were in critical condition.

The storm of rare ferocity - less than 1 percent of all tornadoes reach such wind speed - ripped through scores of buildings in Moore, south of the city. Block after block of the community lay in ruins. Cars and trucks were left crumpled.

The National Weather Service issued an initial finding that the tornado was an EF-4 on the enhanced Fujita scale, the second most powerful type of twister.

In video of the storm, the dark funnel cloud could be seen moving slowly across the landscape, scattering shards of wood, pieces of insulation, shingles and glass over the streets.

At Plaza Towers Elementary School, the storm tore off the roof, knocked down walls and turned the playground into a mass of twisted plastic and metal.

Several children were pulled alive from the rubble. Rescue workers passed the survivors down a human chain to a triage center in the parking lot.

James Rushing, who lives across the street from the school, heard reports of the approaching tornado and ran to the school, where his 5-year-old foster son, Aiden, attends classes. Rushing believed he would be safer there.

"About two minutes after I got there, the school started coming apart," he said.

The students were placed in the restroom.

Downed power lines and open gas lines posed a risk in the aftermath of the storm, Police Capt. Dexter Nelson said.

The same suburb was hit hard by a tornado in 1999. That storm had the distinction of producing the highest winds ever recorded near the Earth's surface - 302 mph (486 kph).