At least 23 people have died after an "outbreak of tornadoes" across Alabama and the southeast of the US.

Weather officials said the tornados were unleashed by a vast storm system crossing a wide area of the country.

The severe weather destroyed many homes and businesses, leaving a trail of destruction in its wake.

Weather warnings extended into Georgia, Florida and South Carolina.

Emergency workers rushed to join search and rescue efforts in hard-hit Lee County and spent the night pulling the dead and injured from the wreckage.

Death toll

At least 23 people were confirmed dead in Alabama.

Lee County Sheriff Jay Jones said a number of children were among them.

He said several people had been taken to hospital, “some of them with very serious injuries,” while others were reported missing.

“The challenge is the sheer volume of the debris where all the homes were located,” he told CNN.

“It's the most I've seen that I can recall.”

Alabama

Sheriff Jones said the storm's path of destruction stretched for miles through Lee County and in places was about a quarter of a mile wide.

Drones equipped with heat-seeking devices flew overhead to scan the area for survivors but the dangerous conditions halted the search.

Authorities warned that the death toll could rise further as search efforts continued.

The National Weather Service confirmed that a tornado with at least an F3 rating and a track at least half a mile wide caused the devastation in Alabama.

It said radar and video evidence showed what looked like a large tornado crossing the area near Beauregard shortly after 2pm.

US President Donald Trump tweeted late Sunday: "To the great people of Alabama and surrounding areas: Please be careful and safe... To the families and friends of the victims, and to the injured, God bless you all!"