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

There were at least 45 reports of tornado damage across Texas, Louisiana, Mississippi, Alabama and Georgia, said Brian Hurley, a meteorologist with the National Weather Service’s Weather Prediction Center. Crews will do damage surveys to confirm tornadoes.

The storms during busy holiday travels caused some treacherous road conditions along with delays or cancellations at some of the busiest U.S. airports. As of Sunday afternoon, there were over 600 flight delays affecting Hartsfield-Jackson Atlanta International Airport, according to flight tracker FlightAware.

“It’s not unheard of, but it is fairly uncommon to have a severe weather outbreak of this magnitude this late in the year,” said Frank Pereira, a meteorologist with the Weather Prediction Center.

In the Houston area, National Weather Service storm survey crews confirmed that at least five tornadoes hit north and south of the city on Saturday.

At least one person died. The 48-year-old woman was found about 100 feet (30 meters) 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 had injuries that weren’t considered critical, said Polston, adding that at least 40 homes and buildings were significantly damaged.

About 30 Homes Destroyed in Montgomery County

In Montgomery County, north of Houston, about 30 homes were destroyed and about 50 others sustained major damage, county official Jason Smith said.

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

“It’s very sad, just terrible timing,” Maffucci said, adding that the storms were responsible for a number of downed trees and “quite a few wrecks.”

Two people were killed in storms in Mississippi, officials said. An 18-year-old died after a tree fell on her home Saturday night in Natchez in Adams County, said 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 city of Athens, northwest of Huntsville.

Holly Hollman, spokeswoman for the city, said most of the damage from the early Sunday morning storms occurred downtown. She said it hurled large HVAC units from the tops of building and ripped the roof off a bookstore. A full-sized, stripped-down military helicopter was toppled from a pole where it was on display, she added.

“I stepped out on my porch and I could hear it roar,” she said of the storm. “I think we are extremely lucky that we got hit late at night. If it had hit during the busy hours, I think we might have had some injuries and possibly some fatalities.”

Over 40,000 Without Power

As of Sunday afternoon, over 40,000 people were still without power in Mississippi, according to electric utility tracking website PowerOutage.us. Texas, Alabama, North Carolina and Georgia each had about 10,000 customers without power, it said.

The storms closed some roads in western North Carolina, a region broadly devastated by Hurricane Helene this fall. That included part of U.S. 441, also known as the Great Smoky Mountains Expressway, which closed north of Bryson City due to high winds.

In Bumpus Cove, Tennessee, Justin Fromkin, president of Raising Hope Disaster Relief, worked Sunday to save what he could from the organization’s supply tent — filled with clothes and food — after about 6 inches (152 millimeters) of rain fell.

He’s spent the past few months delivering aid to areas in western North Carolina and eastern Tennessee that are still reeling from Helene. The ground in some parts of the mountains is still unstable from Helene, Fromkin said, and Sunday’s downpour adds to the problem.