Powerful storms have swept across the southern United States after unleashing suspected tornadoes and flooding that killed at least eight people, including three children.

Nearly 90,000 customers were without power in Texas, Mississippi, Louisiana, Arkansas, and Georgia as of midday on Sunday, as the severe weather left a trail of destruction.

Two children were killed on a back road in East Texas when a pine tree fell onto the car in which they were riding in a severe thunderstorm on Saturday near Pollok, about 150 miles south east of Dallas.

The tree “flattened the car like a pancake”, said Captain Alton Lenderman of the Angelina County Sheriff’s Office.

The children, aged eight and three, were pronounced dead at the scene, although both parents, who were in the front seat, escaped injury, he said.

At least 25 people were taken to hospitals for treatment after a suspected tornado struck the Caddo Mounds State Historic Site in East Texas during a Native American cultural event in Alto, said Police Chief Jeremy Jackson. At least eight were critically hurt.

There was widespread damage in Alto, a town of about 1,200, and the school district cancelled classes until its buildings can be inspected to ensure they are safe.

A tornado flattened much of the south side of the central Texas town of Franklin, overturning mobile homes and damaging other residences, said Robertson County Sheriff Gerald Yezak.

The weather service said preliminary information showed an EF-3 tornado touched down with winds of 140 mph.

The tornado destroyed 55 homes, a church, four businesses, a duplex, and part of the local housing authority building, authorities said.

Two people were taken to hospital for injuries that were not thought to be life-threatening, while others were treated at the scene, Mr Yezak said.

Heavy rains and storms battered Mississippi into the night on Saturday as the storms moved east.

A 95-year-old man died after a tree crashed onto his caravan in north eastern Mississippi, Monroe County Road Manager Sonny Clay said at a news conference, adding that a tornado had struck.

Nineteen residents were taken to hospitals, including two in critical condition. A tornado was reported in the area 140 miles south east of Memphis, Tennessee, at the time.

National Weather Service meteorologist John Moore said a possible twister touched down in the Vicksburg, Mississippi, area.

No injuries were reported there, but officials said several businesses and vehicles were damaged.

The storm damaged a roof of a hotel in New Albany, Mississippi, and Mississippi State University’s 21,000 students huddled in basements and hallways as a tornado came near the school’s campus in Starkville.

Severe Weather Texas
A car lies upside down in a ditch following a suspected tornado (Laura McKenzie/College Station Eagle via AP)

University spokesman Sid Salter said some debris, possibly carried by the tornado, was found on campus, but no injuries were reported and no buildings were damaged.

Trees were toppled and minor damage was reported in residential areas east of the campus.

The large storm system also unleashed flash floods in Louisiana, where two deaths were reported.

Thirteen-year-old Sebastian Omar Martinez drowned in a drainage canal after flash flooding struck Bawcomville, near Monroe, said Deputy Glenn Springfield of the Ouachita Parish Sheriff’s Department.

Separately, one person died when a car was submerged in floodwaters in Calhoun, also near Monroe.

As the storm moved into Alabama, a possible tornado knocked out power and damaged mobile homes in Troy, about 50 miles south of Montgomery.

A county employee died after being struck by a vehicle while he was helping clear away trees about 2:15am on Sunday near the Birmingham suburb of Hueytown, said Captain David Agee of the Jefferson County Sheriff’s Office.

The man, whose name was not released, died after being taken to a hospital.