A tornado swept through Oklahoma City, flattening dozens of homes and scattering cars and mobile homes across the landscape. Strong winds also tore off roofs in eastern Kansas, and may have been the cause of a train derailment there.
At least 118 people were injured in the Oklahoma City area, 20 critically, said Paul O'Leary, spokesman for the city's ambulance service. There were no immediate reports of fatalities.
The twister struck just as the afternoon rush hour was beginning, ripping roofs off homes and businesses and damaging a General Motors plant.
Governor Brad Henry said officials in Moore, just south of the city, reported 1,500 homes damaged and about 300 destroyed.
Truck driver David Waller was on Interstate 40 when he saw the tornado coming his way. He parked his 18-wheeler and ran for a clump of bushes. He and two other men clung to a tree as the tornado passed by.
"I'm scared to death," said Waller, who was shaking, his clothes covered with mud. His truck was picked up by the tornado and dropped on its side.
For many Oklahomans, the tornado was eerily reminiscent of one that ripped through the Oklahoma City area on May 3, 1999, killing 44 people.
"Some of those very same parts were hit again today," Governor Henry said. "Nature can be cruel, but Oklahomans are a resilient people and we will face this crisis with strength and resolve."
Tornado sirens sounded just before 5pm and the twister touched down in suburban Moore 15 minutes later. Shrouded by rain, it moved over a highway and a shopping mall before moving to the northeast and into two more suburbs.
Steve McManus, assistant fire chief in Midwest City, said about 100 homes were damaged or destroyed in Midwest and Oklahoma City.
Officials at Tinker Air Force Base said the storm damaged a fence line along the base but that there were no injuries.
Some 37,000 customers in the area were without power, Oklahoma Gas and Electric said.