Tornadoes have killed at least 18 people -- including 10 in one small Arkansas community -- from a line of severe thunderstorms now threatening to bring high winds, hail and possible twisters to southern Kentucky and Tennessee into Mississippi and Alabama.
Forecasters say Jackson and Tupelo in Mississippi and Huntsville, Ala., are in the highest risk area for severe weather.
As of early Monday morning, 30 tornadoes were reported overnight in seven states, according to the Storm Prediction Center (SPC) in Norman, Okla.
At least 10 people were killed in the small community of Vilonia north of Little Rock in central Arkansas by a huge twister that ripped homes from foundations and flipped cars.
Thehalf-mile wide twister also slammed into nearby Mayflower, carving a 30-mile trail of death an destruction.
"It's just devastating," Sheriff Andy Shock of Faulkner County, Ark., tells KTHV-TV after surveying damage in Vilonia, which has a population of 3,800.
He said he expects the death toll to rise as rescue teams search the debris.
Among the ruins was a new $14 million intermediate school in Vilonia that was set to open this fall in the town north of Little Rock.
"There's just really nothing there anymore. We're probably going to have to start all over again," said Vilonia school superintendent Frank Mitchell said.
Major damage was also reported in Mayflower, where homes and buildings were leveled.
"It turned pitch black," said Mark Ausbrooks, who was at his parents' house in Mayflower when the storm arrived. "I ran and got pillows to put over our heads and ... all hell broke loose."
Speaking to The Associated Press, he added: "My parents' home, it's gone completely
The Arkansas National Guard has activated 46 members and dispatched them to the two hard-hit towns.
Brandon Morris with the state Department of Emergency Management said one person is confirmed dead in White County, Ark., the television station reported. At least five people were killed in Pulaski county, including three on one street.
Interstate-40, littered with overturned vehicles 22 miles northwest of Little Rock, was shut down in both directions.
"About 30 vehicles — large trucks, sedans, pickup trucks — were going through there when the funnel cloud passed over," Bill Sadler, a spokesman for the Arkansas State Police, told the Associated Press.
One person was also killed in Oklahoma and one in Iowa.
One twister hit the small northeastern Oklahoma town of Quapaw, killing one person, according to Ottawa County sheriff dispatcher Kelli Soechs.
After hitting Quapaw, the tornado moved north to Kansas and hit Baxter Springs about 5 miles away. Cherokee County, Kan., sheriff's dispatcher Josh Harvey said the tornado injured several people.
Emergency officials in Iowa said at least one person was killed by a twister in Keokuk County.
Contributing: William M. Welch; The Associated Press