A fierce tornado blasted through Little Rock, Arkansas, and neighbouring towns on Friday (Mar 31), killing at least two people and injuring dozens of others as it sheared roofs and walls from many buildings, flipped over vehicles and downed trees and power lines, officials said.
Hours later another tornado or extreme burst of wind was believed to have ripped open the roof of an auditorium in northern Illinois, causing a ceiling collapse, while a rock band was performing on stage, officials said.
One person died and 28 others were rushed by ambulance to area hospitals, five of them with serious injuries, Shawn Schadle, the fire chief in Belvidere, a riverside town near the border with Wisconsin, told reporters.
He said about 260 people were attending the concert at the city's Apollo Threatre, which featured the band Morbid Angel as part of the group's "Tour of Terror."
The mid-afternoon twister in Arkansas and the storm in Illinois were both spawned by one of numerous violent thunderstorms raking a vast swath of the US heartland as part of a much larger expanse of extreme spring weather.
The University of Arkansas for Medical Sciences hospital, the region's only major trauma centre, declared a level-1 mass casualty alert after the tornado struck Little Rock, the state's capital and most populous city, at mid-afternoon.
Arkansas Governor Sarah Huckabee Sanders told a late-night news conference the tornado claimed at least two lives in Wynne, about 160km east of Little Rock near the Tennessee border.
Nearly 30 people in Little Rock were transported by fire department and other emergency personnel to area hospitals for injuries, Mayor Frank Scott Jr told reporters, adding that "by the grace of God, we have not experienced any fatalities".
Police said several areas in the western end of the city were hardest hit, and the mayor described property damage as "extensive".
In the adjoining town of North Little Rock, just across the Arkansas River from the capital, Baptist Health Medical Center reported treating 11 patients from the storm, one of them in critical condition. Television station KTHV-TV reported one storm-related death in North Little Rock, but that could not be immediately confirmed.
Between five and 10 other patients were treated at the emergency department of the Unity Health hospital in nearby Jacksonville, administrator Kevin Burton said.
Wynne Police Chief Richard Dennis was quoted by television station KAIT8-TV in Jonesboro, Arkansas, as describing the storm's aftermath in his town as "total destruction", adding that dozens of people had been trapped in debris.
Aerial footage posted by The Weather Channel showed a heavily damaged area of Little Rock spanning several blocks with numerous homes missing roofs and walls, some of them collapsed, and overturned vehicles littering streets. KATV posted an image of a heavily damaged high school in the town of Wynne.
The turbulent weather came one week after a previous swarm of thunderstorms unleashed a deadly tornado that devastated the Mississippi town of Rolling Fork, destroying many of the community's 400 homes and killing 26 people.
CLOSE CALL IN NAIL SALON
Video shot on Friday from a window in a Baptist Health facility and verified by Reuters showed a towering, swirling black column of air, moisture and dust plowing slowly through the landscape in the near distance.
One woman recounted in a live interview aired by KATV that she was visiting a salon to have her nails done when she looked out the window and saw leaves swirling moments before the building's roof was torn off.
She and others in the shop took cover in a back room as the twister struck and emerged to find the ceiling gone, said the woman, who seemed unhurt.
Governor Sanders said she had mobilized about 100 National Guard troops to assist in the emergency response, and signed an executive order to immediately authorise US$250,000 from the state disaster response and recovery fund.
The twister struck as a blast of extreme spring weather swept much of the United States, menacing the nation's midsection from Texas to the Great Lakes with thunderstorms and tornados.
The National Weather Service (NWS) was tracking at least three dozen unconfirmed tornado reports in Arkansas, Tennessee, Illinois and Iowa.
Tens of millions of Americans across the Great Plains, Midwest, South and East were under warnings and advisories for various weather hazards on Friday evening and into the weekend, the NWS said.
Besides Arkansas, southern Missouri, western Kentucky and western Tennessee were deemed at greatest risk of severe thunderstorms capable of producing violent tornados, large hail and damaging winds, the weather service said.
The northern, colder edge of the storm system, stretching from the High Plains to the upper Great Lakes, was expected to bring heavy snow, combining with winds gusting up to 80kmh to create blizzard conditions.