"We have debris" is the key phrase that lets storm chasers know they are dealing with a twister. The swirling winds scatter debris in all directions.
Friday night, after multiple tornadoes touched down, Oklahoma City and the surrounding area was without power, pelted by rain and hail, and endangered by flooding. Tree limbs and wrecked cars blocked roads.
The storm changed direction so quickly that even experienced storm chasers were caught by surprise, and a Weather Channel vehicle was destroyed.
The massive storm also struck Norman, Okla., home of the state university, and warnings were issued for counties in Illinois and Missouri.
Mick Cornett, mayor of Oklahoma City, said that Friday's storm did not appear as powerful as the one that devastated the suburb of Moore less than two weeks ago, which he described as "an extremely unusual and dangerous storm."
Late Friday about 80,000 people were without power in Oklahoma, 64,000 of them in the Oklahoma City metro area.
There were numerous injuries, some critical. A mother and her baby died when their SUV flipped over on I-40. At least three other people were killed in their vehicles, authorities say.
Mayor Cornett said "the absolute worst place you can be" during a tornado is in a car.
Describing conditions as "particularly dangerous," the National Weather Service had declared tornado watches over large areas of Oklahoma, Kansas and Missouri through late Friday and severe storm warnings over an area stretching from Minnesota and Michigan south to Arkansas.
Late Friday, Missouri Gov. Nixon declared a state of emergency "as a widespread severe weather system continued to move across the state, bringing heavy rain, hail, straight-line winds, flooding and radar-indicated tornadoes," said the statement from the governor's office.
"Much of Missouri is experiencing dangerous severe weather tonight, on the heels of several days of heavy rain," Gov. Nixon said. "I urge Missourians to closely monitor weather conditions, so they can take shelter or move to higher ground if needed. The risk of severe weather remains with us well into tomorrow. The state of Missouri will continue to work closely with local officials to help protect lives and property from these storms."
Gov. Nixon has also activated the Missouri State Emergency Operations Plan, which allows state agencies to coordinate directly with local jurisdictions to provide emergency services.
In Oklahoma as well as Missouri, dangerous conditions were expected to continue overnight and into Saturday.
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