A huge tornado with winds of up to 200 miles per hour tore through the Oklahoma City suburb of Moore on Monday (May 20), ripping up at least two schools and leaving a wake of tangled wreckage as a dangerous storm system threatened as many as 10 U.S. states.

Aerial video showed tracts of homes destroyed, cars tossed about and piled atop one another, and at least one building on fire. Rescue workers were pulling children from a severely damaged elementary school in Moore, a KFOR television reporter said from the scene, and aerial video showed first responders sifting through the rubble left behind.

The National Weather Service assigned the twister a preliminary ranking of EF4 on the Enhanced Fujita Scale, meaning the second most powerful category of tornado with winds up to 200 mph.

There were no immediate reports of deaths and the number of injuries remained unconfirmed after the tornado struck in mid-afternoon.

The massive twister struck at the height of tornado season, and more were forecast. On Sunday (May 19), tornadoes killed two people and injured 39 in Oklahoma.

Witnesses said Monday's tornado appeared more fierce than the giant twister that was among the dozens that tore up the region on May 3, 1999, killing more than 40 people and destroying thousands of homes. That tornado ranked as an EF5, meaning it had winds over 200 mph.

The tornado season in the United States had been unusually quiet until last week, when a tornado struck the town of Granbury, Texas, killing six people.

Presented by Adam Justice