A storm-related death has been reported in Hughes County, Oklahoma. The affiliate report cited Hughes County Emergency Management, saying the death occurred in Holdenville, 75 miles southeast of Oklahoma City.

The Oklahoma Department of Emergency Management said there were reports of injuries, property damage, flooding, downed power lines and trees in several counties Saturday night. The extent of the damage was unclear early Sunday.

Sulphur, about 80 miles south of Oklahoma City, saw injuries and impacts from at least two major tornadoes overnight when a flood warning was issued for the city, according to the weather service.

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"South of Sulphur, there was a large and extremely dangerous tornado traveling north at 35 miles per hour. First responders urgently need to prepare for additional tornado impacts!!!" The weather service in Norman warned.

As communities in Nebraska and Iowa surveyed the devastation left behind by the storms, nearly 47 million people were at risk from severe weather on Sunday from east Texas northward to the upper Mississippi River Valley.

Cities such as Dallas and Austin in Texas, Oklahoma City and Tulsa in Oklahoma, Wichita and Topeka in Kansas, and the Kansas City metropolitan area could see strong tornadoes as storms move eastward across the southern Plains.

More than 7 million people are under surveillance due to the tornado, which early Sunday stretched more than 800 miles from Texas to southern Wisconsin.The watch areas will expire between 03:00 and 07:00 CT.

Two tornadoes were spotted crossing Highway 9 between Goldsby and Blanchard in Oklahoma late Saturday, as well as just east of Tinker Air Force Base, the weather service reported. As the tornado moved toward Norman, University of Oklahoma students and staff were urged to "Take shelter inside your building NOW.Go to the lowest floor/inner room."

Oklahoma's emergency operations center was activated on Saturday, according to a Facebook post by Governor Kevin Stitt. "Pay attention to the weather and know where to take shelter if a severe storm threatens your area," he told residents.