Officials were beginning to assess the damage on Sunday after a strong storm system moved across the southern U.S. over the weekend, spawning tornadoes across the region and killing at least four people.

The line of severe weather led to about 40 tornado reports from southeastern Texas to Alabama, National Weather Service meteorologist Frank Pereira said, but those reports remain unconfirmed until damage surveys are completed.

“It’s not unheard of, but it is fairly uncommon to have a severe weather outbreak of this magnitude this late in the year,” he said.

In the Houston area, National Weather Service crews planned to conduct surveys Sunday for at least five tornados that hit north and south of the city on Saturday. At least one person died.

The 48-year-old woman killed was found about 100 feet from her home in the Liverpool area south of Houston, said Madison Polston of the Brazoria County Sheriff’s Office. She said the exact cause of death wasn’t immediately known.

Four other people in Brazoria County suffered injuries that weren’t considered critical, said Polston, who added that at least 40 homes and buildings were significantly damaged in the county.

In North Carolina, a 70-year-old man was killed Sunday in Statesville, just north of Charlotte, when a tree landed on top of the pickup truck he was driving. Highway Patrol Trooper DJ Maffucci said “it was just a freak accident” and that he believes Matthew Teeple, of Cleveland, North Carolina, was killed instantly.

“It’s very sad, just terrible timing is pretty much all it was,” Maffucci said.

The storms also were responsible for a number of downed trees in the area and “quite a few wrecks,” Maffucci added.

Two people were killed in storms in Mississippi, including a teen, officials said. The 18-year-old died after a tree fell on her home Saturday night in Natchez in Adams County as the storm brought high winds to the area, said Adams County Emergency Management spokesperson Neifa Hardy. Two other people in the home were injured.

Another person died in Lowndes County and at least eight more were injured across the state, officials said.

The National Weather Service said two tornadoes hit around Bude and the city of Brandon, ripping roofs from several buildings.

Storm damage also was reported in the northern Alabama town of Athens, just northwest of Huntsville. A National Weather Service survey team was expected to begin assessing damage Sunday morning, said meteorologist Chelly Amin.

Holly Hollman, spokeswoman for the city of Athens, said she lives about two blocks from downtown, where most of the damage from the early Sunday morning storms occurred.

Hollman said the storm hurled large HVAC units from the tops of building, ripped the roof off a bookstore and damaged a brick building adjacent to a veteran’s museum.