Tornadoes touched down in the upper Midwest and northern Arkansas, killing at least two people, as a spring-like storm system posed a risk to 45 million people.
Compact but strong storms known as supercells raked parts of the central U.S. on Tuesday, causing damage from Arkansas to Iowa and Illinois. Wind-whipped wildfires destroyed homes in Texas.
At Ottawa, Illinois, state Emergency Management Agency spokeswoman Patti Thompson said a tornado victim was killed by an uprooted tree. Minor injuries were also reported at an Ottawa nursing home, but Thompson said the number of those hurt in the twisters was not known.
Meanwhile, one person was killed when an apparent tornado ripped through Perry County, Missouri, about 80 miles south of St. Louis. Eight to 10 homes near the small town of Perryville were badly damaged and winds were so strong that several vehicles were blown off of Interstate 55. Perry County Clerk Jared Kutz said search and rescue crews were going door-to-door and checking the highway to see if there were other victims.
Missouri Gov. Eric Greitens said in a statement that a tornado was confirmed in Perry County. Authorities have not released any information about the person killed.
Forecasters were particularly concerned that the worst of the weather developed after nightfall — and worried it would continue overnight and hit communities while people slept.
While weather conditions typically improve after nightfall, as the atmosphere cools, the Storm Prediction Center posted tornado watches late Tuesday for the area from eastern Kansas and Oklahoma to near Cincinnati. It warned that significant tornadoes with winds above 111 mph were possible until 4 a.m. Central time.
"Some increase in storm coverage is likely through the overnight hours," one of its advisories said.
The Oklahoma-based forecast center said 45 million people from Texas to Ohio faced some risk of bad weather. The highest threat level in effect, warning of a "moderate risk" for severe weather, covered the area from southwestern Missouri into Indiana.
Hundreds of people, including many school children, took shelter at Bald Knob High School in Arkansas after a tornado warning was posted for the area. The school is hosting a state basketball tournament for smaller schools this week. Moments earlier, the storm caused damage in Higginson, a town of 621, the White County Sheriff's Office said.
Photos posted on social media showed basketball fans on the floor in the school's designated safe area.
The Bald Knob storm was part of the same system that produced a wall cloud near Mayflower, Arkansas, which was hit in 2014 by a tornado with winds approaching 200 mph. The storm crossed Interstate 40 between Little Rock and Conway, but there were no reports that a funnel cloud touched down.
The Storm Prediction Center had warned that some of Tuesday's storms would track over long distances. The Arkansas storm held together for more than 100 miles, though it did not produce tornadoes.
The Missouri Department of Transportation closed Interstate 55 in both directions because of storm damage in Perryville.
Drivers stopped along U.S. 60 east of Springfield, Missouri, according to the Wright County Sheriff's Office. The storm system pelted some areas with large hailstones, including some the size of baseballs in central Illinois.
Forecaster Ariel Cohen, who raised Tuesday's threat level in a midday update, said sunshine warmed the region and roiled the atmosphere ahead of an approaching cold front. The threat is expected to shift to the Southeastern U.S. on Wednesday.
Strong winds elsewhere in the Plains spread wildfires in Texas. Four homes were destroyed near Tulia, about 50 miles south of Amarillo, before firefighters beat back the flames. Texas A&M Forest Service spokesman Phillip Truitt said the fire prompted the evacuation of almost 1,200 homes.