President Joe Biden issued an emergency declaration for Mississippi early Sunday, making federal funding available to the areas hardest hit Friday night by a deadly tornado that ripped through the Mississippi Delta, one of the poorest regions of the US.

At least 25 people were killed and dozens of others were injured in Mississippi as the massive storm ripped through several towns on its hour-long path. One man was killed after his trailer home flipped several times in Alabama.

Search and recovery crews on Sunday resumed the daunting task of digging through the debris of flattened and battered homes, commercial buildings and municipal offices after hundreds of people were displaced, even as the National Weather Service warned of a risk of more severe weather Sunday — including high winds, large hail and possible tornadoes — in eastern Louisiana, south central Mississippi and south central Alabama.

Following Biden’s declaration, federal funding can be used for recovery efforts in Mississippi’s Carroll, Humphreys, Monroe and Sharkey counties, including temporary housing, home repairs, loans covering uninsured property losses and other individual and business programmes, the White House said in a statement.

The twister flattened entire blocks, obliterated houses, ripped a steeple off a church and toppled a municipal water tower.

Based on early data, the tornado received a preliminary EF-4 rating, the National Weather Service office in Jackson said late Saturday in a tweet. An EF-4 tornado has top wind gusts between 166 mph and 200 mph (265 kph and 320 kph), according to the service. The Jackson office cautioned it was still gathering information on the tornado.

The tornado devastated a swath of the 2,000-person town of Rolling Fork, reducing homes to piles of rubble and flipping cars on their sides. Other parts of the Deep South were digging out from damage caused by other suspected twisters. One man died in Morgan County, Alabama, the sheriff’s department there said in a tweet.

Pope Francis offered a special prayer for the people of Mississippi “hit by a devastating tornado” during his weekly noon blessing overlooking St Peter’s Square in Vatican City on Sunday.

“How anybody survived is unknown by me," said Rodney Porter, who lives 20 miles (32 kilometres) south of Rolling Fork. When the storm hit Friday night, he immediately drove there to assist in any way he could. Porter arrived to find “total devastation” and said he smelled natural gas and heard people screaming for help in the dark.

“Houses are gone, houses stacked on top of houses with vehicles on top of that,” he said.

Annette Body drove to the hard-hit town of Silver City from nearby Belozi to survey the damage. She said she was feeling “blessed” because her own home was not destroyed, but other people she knows lost everything.

“Cried last night, cried this morning,” she said, looking around at flattened homes. “They said you need to take cover, but it happened so fast a lot of people didn’t even get a chance to take cover.”

Storm survivors walked around Saturday, many dazed and in shock, as they broke through thickly clustered debris and fallen trees with chain saws, searching for survivors. Power lines were pinned under decades-old oaks, their roots torn from the ground.

Mississippi Governor Tate Reeves issued a state of emergency and vowed to help rebuild as he viewed the damage in a region speckled with wide expanses of cotton, corn and soybean fields and catfish farming ponds. He spoke with Biden, who also held a call with the state’s congressional delegation.

More than a half-dozen shelters were opened in Mississippi to house those who have been displaced.