A tornado roaring across southeast Alabama killed at least 23 people, including children, and injured several others on Sunday as severe storms destroyed mobile homes, snapped trees and caused widespread destruction.

Dozens of emergency responders rushed to join search and rescue efforts in Lee County, Alabama, after what appeared to be a large tornado touched down on Sunday afternoon, springing out of a powerful storm system raking the Southeast.

"Unfortunately our toll, as far as fatalities, does stand at 23 at the current time," Lee County Sheriff Jay Jones said.

Mr Jones described the damage caused by the storm as "catastrophic, based on the destruction of homes that we've seen."

"The devastation is incredible," he said. "I cannot recall at least in the last 50 years... a situation where we have had this loss of life that we experienced today."