Deadly storm bore down on an interstate highway as commuters tried to beat it home during evening rush hour.
Multiple tornadoes hit Oklahoma City and the metro area Friday night, killing at least 5 people and injuring more than 50.
The storm also brought heavy rain and hail. Floodwaters topped 4 feet in Oklahoma City early Saturday and are expected to rise as flash flooding continued in parts of the state. Across east and central Oklahoma, repeated rounds of thunderstorms have produced between 4 to 7 inches of rain since midnight Saturday.
The area along the state's I-40 corridor, packed with motorists when the storm occurred, was particularly hard-hit.
A mother and a child were killed when their car rolled over, KFOR-TV reported.
The Oklahoma Highway Patrol confirms several motorists are missing.
Another person died at El Reno, the first city struck by the storm, said Amy Elliott, a spokeswoman for the state medical examiner. Details on the two other deaths were not available, Elliott said.
Saturday, Elliott told the Associated Press that she had no word of additional fatalities beyond the five reported.
A tornado was reported on the ground in Moore, where a mammoth May 20 twister killed 24 people and left the southern Oklahoma City suburb in ruins, KOKH-TV reported.
Will Rogers World Airport, southwest of Oklahoma City, was closed Friday evening and reopened overnight.
Rick Smith, the warning coordination meteorologist for the National Weather Service at Norman, said that while the storm packed a powerful punch, with winds estimated at 80 mph, it wasn't as strong as the Moore tornado.
Smith also said it was fortunate that the storm largely bypassed the center of the city.
The Oklahoma Corporation Commission reported at least 86,200 power outages related to the storms as of early Saturday.
In Missouri, the combination of high water and fallen power lines closed dozen of roads, snarling traffic on highways and side streets in the St. Louis area. At the Hollywood Casino in suburban of Maryland Heights, gamblers rushed from the floor as a storm blew out windows and tore off part of the roof.
Weather Channel meteorologist Mike Bettes sustained minor injuries after the "tornado hunt" car in which he was riding in Oklahoma was thrown some 200 yards by a tornado.