17 tornadoes reported in 7 states across the Plains

At least 17 tornadoes were reported in seven states overnight into Tuesday morning.

The twisters were reported in Iowa, Nebraska, Kansas, Oklahoma, Missouri, Tennessee and South Dakota.

The most destructive storm appeared to have been in Barnsdall, Oklahoma, north of Tulsa, where major damage was reported. One person was killed in Barnsdall, according to Osage County Sheriff Eddie Virden.

Fifteen people were treated for injuries at Ascension St. John Jane Phillips Medical Center in Bartlesville, about 20 miles south of Barnsdall.

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In addition to tornadoes, 4-inch hail, about the size of a softball, was reported in Kansas.

A tornado watch had been issued Tuesday morning for parts of Missouri -- including St. Louis -- and Illinois. That watch was to be in effect until 8 a.m. local time.

The tornado watch in Arkansas was also extended to 5 a.m. local time.

NOAA's Storm Prediction Center in Norman, Oklahoma, had issued the highest-possible severe weather risk alert for multiple intense, long-track tornadoes Monday afternoon and evening.

ABC News' Kenton Gewecke and Melissa Griffin contributed to this report.