More than 20 million people are at risk of experiencing severe storms Sunday across much of the southern United States and portions of the Midwest.

Search and rescue efforts are continuing in Mississippi after a deadly tornado hit the US state, leaving at least 25 people dead and causing the state government to declare a state of emergency on Saturday in all counties affected by the severe storms.

At least one person has also been killed in the state of Alabama. Four people are missing and dozens more have been left injured by Friday’s tornado, which devastated several rural towns, with Rolling Fork in Mississippi’s hard-hit western Sharkey County almost entirely wiped out.

Mississippi State Gov. Tates Reeves, who is heading to Sharkey County with state emergency officials, said: “I’m devastated by the destruction and loss of life that these storms have caused.”

“The state of Mississippi will continue doing everything we can to marshal every resource available to support our fellow Mississippians who are in need. The state will be there to help them rebuild,” he added.

“We’re not going anywhere and we’re in it for the long haul. Please join me in praying for the family and friends of those who lost loved ones in this trying time.”

Reeves, who visited Silver City and Winona on Saturday to meet with affected residents hit by the tornado’s fury, described the situation as a “tragedy”, writing: “We are blessed with brave, capable responders and loving neighbours. Please continue to pray.”

US President Joe Biden described the images coming out of Mississippi as “heartbreaking”, and said: “We will be there as long as it takes. We will work together to deliver the support you need to recover.” He added that the federal government would “do everything we can to help”.

Several state agencies are “responding to the devastating tornadoes that swept through the state overnight,” a press release from Mississippi Emergency Management Agency (MEMA) said Saturday, adding: “Life safety is the number one priority, and damage assessments will begin soon.”

More storms are expected to hit parts of Alabama and Georgia Sunday morning, potentially bringing with it the threat of large hail. These storms will then push east into the Carolinas by Sunday afternoon, posing a threat of damaging winds.

Additional storms are expected to form across portions of eastern Texas on Sunday afternoon and are forecast to push into Louisiana, Mississippi, and eventually Alabama through the afternoon and evening. These storms will be capable of producing large to very large hail, a few tornadoes, and damaging winds.