Tornadoes unleashed by thunderstorms along the U.S. Gulf Coast ripped through southeastern Mississippi on Tuesday, killing four people, injuring many others and causing extensive damage, authorities said.

One of the heaviest-hit areas was a commercial district along a Highway 98 bypass in the town of Columbia in Marion County, about 50 km west of Hattiesburg, state emergency management spokesman Greg Flynn said.

"We've got whole roofs lying in the road, people trapped in houses, cars flipped over. . . . "It's chaos over here," Marion County Sheriff Berkley Hall said of the aftermath of the storm, which struck at about 2:30 p.m.