Alabama tornado: More than 20 dead as powerful storms destroy homes

US President Donald Trump urges residents to be 'safe'

A funnel-shaped cloud near Marianna, Florida. AP Photo

This photo shows debris in Lee County, Alabama, after what appeared to be a tornado struck in the area. AP Photo

People walk amid debris in Lee County, Alabama. AP Photo

Emergency responders work in the scene amid debris in Lee County, Alabama. AP Photo

A fallen cell tower lies across a highway in Lee County, Alabama. AP Photo

A vehicle is caught under downed trees in Beauregard, Alabama. AP Photo

Damage in Smiths Station, Alabama. AP Photo

At least 22 people, some of them children, died after a tornado swept through Lee County, Alabama on Sunday, and the death toll was expected to rise as rescuers searched through the rubble of destroyed homes, authorities said.

Emergency workers faced a grim night of pulling the dead and injured from the wreckage of homes and businesses.

"The challenge is the sheer volume of the debris where all the homes were located," Lee County Sheriff Jay Jones told CNN. "It's the most I've seen that I can recall."

Storms, including at least one apparent tornado, uprooted trees and destroyed homes in neighbouring Georgia, initially knocking out power to 21,000 customers, said Georgia Power spokeswoman Meredith Stone. That number was reduced by more than half later on Sunday evening, she said.

On Twitter, US President Donald Trump urged residents of Alabama and other areas affected by the storms to be "careful and safe."

"Tornadoes and storms were truly violent and more could be coming," Mr Trump wrote. "To the families and friends of the victims, and to the injured, God bless you all!"

In Alabama, Lee County Coroner Bill Harris said the death toll could rise.

"We've still got people being pulled out of rubble," he told the Birmingham News. "We're going to be here all night."

The East Alabama Medical Centre in Opelika said that it was treating more than 40 patients as a result of the tornado and expected to receive more. Some patients had been sent to other hospitals, it added.

Severe weather unleashed one of many possible tornadoes that threatened the Southern United States on Sunday afternoon. Tornado warnings and watches were in effect for parts of Georgia and Alabama through Sunday evening.

Video footage from the small community of Beauregard in Lee County showed homes reduced to piles of wreckage, felled trees, and debris from blasted buildings scattered across roads.

Photos posted on social media from a highway near Smiths Station, about 32km east of Beauregard, showed a large bar called the Buck Wild Saloon with its roof torn off and missing most of a wall after the storm swept through.

Alabama Governor Kay Ivey warned residents on Twitter that more severe weather might be on the way. She said the state was working to help families who had been affected.

"Our hearts go out to those who lost their lives in the storms that hit Lee County today," Ivey wrote. "Praying for their families & everyone whose homes or businesses were affected."

A state of emergency for Alabama, issued on February 23 to deal with flooding, would be extended, she said.

Lee County Schools announced on Twitter that campuses in the county would be closed on Monday.

The National Weather Service office in Birmingham, Alabama, said it was sending three survey teams out on Monday to assess damage in Autauga, Macon, Lee and Barbour counties.

"Please stay out of damaged areas so first responders can do their job," the NWS office said on Twitter.

As thousands faced a night without power, temperatures looked set to fall to near freezing following the storm.