LITTLE ROCK, Arkansas (Reuters) - A tornado caused a "mass casualty situation" in Vilonia, Arkansas, after ripping through the town on Sunday, a spokesman for the Faulkner County Sheriff's office said.
The spokesman said the number of casualties was not immediately known. The tornado also struck the nearby town of Mayflower.
A spotter in Mayflower, Arkansas, 35km north-west of Little Rock, reported a 800m-wide tornado crossing Interstate 40 at about 7.30pm, the National Weather Service said.
At least one person was killed in a tornado in a small Oklahoma town in the north-east corner of the state, according to Ottawa County Sheriff's Department spokesman Derek Derwin. Media and the National Weather Service reported that two people were killed.
That twister was spotted in Quapaw, 322km north-east of Oklahoma City at about 5.45pm, according to the weather service.
An Ottawa County, Oklahoma, police dispatcher said a search and rescue effort was underway in Quapaw, but could not confirm reports of fatalities.
At least a dozen twisters that tore through the central and southern United States on Sunday, leaving behind damaged structures and downed trees and power lines.
Tornadoes were also reported in parts of Iowa, Kansas, Nebraska and Missouri on Sunday afternoon and evening, causing some damage but no known injuries, according to local officials and the weather service.
Trained spotters reported several tornadoes, with at least one touching down in southern Bates County, Missouri, said Brad Vermaas, the county's deputy director of emergency management. Debris, apparently mostly trees, were left in the tornado's path, he said.
A dispatcher for the Bates County sheriff's office said people reported damage in the tornado's wake.