(USA TODAY) -- 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 central Arkansas community of Vilonia north of Little Rock by a huge twister that ripped homes from foundations and flipped cars.
"It's chaos here," James Firestone, mayor of Vilonia, tells CNN. "Our downtown area seems like it's completely leveled."
"There's a few buildings partially standing, but the amount of damage is tremendous," he said. "There's gas lines spewing. Of course, power lines down. Houses are just a pile of brick."
The half-mile wide twister also slammed into nearby Mayflower, carving a 30-mile trail of death an destruction. The Arkansas National Guard sent 46 members to the two hard-hit towns.
"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 is a new $14 million intermediate school in Vilonia that was set to open this fall.
"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.
"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."
In the Mayflower Plantation Subdivision alone, 60 homes sustained extensive damage, Faulkner county officials report, according to KHTV.
Residents have been instructed to stay off the streets and to boil their water before using. Shelters have been opened at the Mayflower high school and middle school.
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.
The twister shredded cars, trucks and 18-wheelers stuck along Interstate 40 north of Little Rock. After the storm passed, tractor-trailer rigs tried to navigate through the damage to continue their journeys, while gawkers held smartphones to their windows to offer a grim glimpse of the destruction.
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