A massive storm system raked the southeast U.S. on Wednesday, spawning tornadoes and dangerous winds that overturned cars on a Georgia interstate and demolished homes and businesses, killing at least two people.

The storm system tossed vehicles on Interstate 75 in Georgia into the air, onto their roofs and into the grassy shoulder. The highway was closed for a time, and another main thoroughfare remained closed until crews could safely remove downed trees and power lines from the road.

'It sounded like a freight train coming through.... It looked like a bomb hit it.' —Theresa Chitwood in Adairsville, Ga.

WSB-TV in Atlanta aired footage showing an enormous funnel cloud bearing down on Adairsville, about 100 kilometres northwest of Atlanta. Authorities were working to rescue people reportedly trapped in homes and buildings.

The storm decimated that city's downtown area and wiped out parts of a large manufacturing plant, killing at least one person and sending nine to hospitals, Bartow County officials said. Residents said no traces remained of some roadside produce stands — a common sight on rural Georgia's back roads.

One other death was reported in Tennessee after an uprooted tree fell onto a storage shed where a man had taken shelter.

'It looks like a bomb hit'

In Adairsville, the strange mix of debris in one yard showed just how dangerous the storm had been: a bathtub, table, rolls of toilet paper and lumber lay in the grass next to what appeared to be a roof. Sheets of metal dangled from a large tree.

"The sky was swirling," said Theresa Chitwood, who owns the Adairsville Travel Plaza. She said she went outside to move her car because she thought it was going to hail. Instead, the passing storm decimated a building behind the travel plaza and ripped the roof off of a nearby bank.

"It sounded like a freight train coming through," she said. "It looks like a bomb hit it."

Powerful winds ripped through the entire region, with gusts powerful enough to topple tractor-trailers in several places.

Conditions remained ripe for tornadoes into Wednesday afternoon, and authorities were still investigating several sites to determine if damage was caused by twisters. Since Tuesday, the system had caused damage across a swath from Missouri to Georgia.

In recent days, people in the South and Midwest had enjoyed unseasonably balmy temperatures. A system pulling warm weather from the Gulf of Mexico was colliding with a cold front moving in from the west, creating volatility.

One person was reported injured by lightning in Arkansas during the storm's eastward trek. Two people suffered minor injuries when a mobile home was blown off its foundation in Kentucky. Only one minor injury was reported in Mississippi, where officials praised residents for heeding warnings and being prepared.

In Tennessee, officials confirmed that a tornado with peak wind speeds of 185 km/h touched down in Mount Juliet. No serious injuries were reported there, though the path of damage was about 150 metres wide, including homes, a warehouse and an automotive business.