Mississippi.

The storm tore a destructive path across parts of the South, where a tornado in northeastern Louisiana damaged houses and commercial buildings.

Neighbors helped to clean a damaged home in Monroe, La., after a tornado passed through the city on Sunday.

Credit…Nicolas Galindo/The News-Star, via Associated Press

Pockets of the South awoke on Sunday to thunderous rain, squalls and lightning as a storm made its way across East Texas and into northern Louisiana, where a tornado damaged houses and commercial buildings, and into Mississippi, where at least six people died.

The severe weather was expected to reach Tennessee, Alabama, Georgia and the Carolinas.

In Mississippi, the National Weather Service in Jackson issued several tornado warnings and emergencies as people prepared to shelter in place.

At least three people died in Jefferson Davis County, the Mississippi Emergency Management Agency said on social media Sunday night. There was at least one death in Walthall County and two others in Lawrence County, the authorities said. Details about the deaths were not immediately available.

This could be a very difficult day, weather-wise,” Gov. Tate Reeves of Mississippi told residents on Facebook Live earlier in the day. “Please be weather aware. Pay attention. I know that these storms that are coming through can be dangerous.”

As the storms moved east, the National Weather Service issued a tornado watch through 10 p.m. Central time for parts of Alabama and Tennessee.

The storm brought torrential rains to East Texas overnight and into Sunday morning, the National Weather Service said. By Sunday afternoon, a tornado had touched down in Monroe, in northeast Louisiana, destroying houses and damaging planes and structures at a regional airport.

“The images and reports of major tornado damage in the Monroe area are heartbreaking, and my prayers are with the people there,” Gov. John Bel Edwards of Louisiana said on Twitter. “I hope all of Louisiana is on high alert right now.”

Tim McIlveene, 47, who lives in New Orleans and was in Monroe to help his parents through the coronavirus pandemic, received an alert from the National Weather Service about 15 minutes before the tornado touched down.

“It got very dark,” Mr. McIlveene said. “The streetlights came on and it was really windy with really horrible rain.”

“It did not last very long, but it was scary,” Mr. McIlveene added. “We were thankfully spared.”

Sahmeka Deburr, 38, of Monroe said she heard what sounded like someone pounding the walls of her house just after noon. She thought her 12-year-old son was playing in the next room, but then she heard a window shatter.

“My son came in the room and said he was scared, and the lights went out,” Ms. Deburr said. “I woke everyone up and we ran in the bathroom and closed the door.”

Ms. Deburr said the tornado lasted only a few minutes. When she went outside to assess the damage, she said, she saw her neighbors’ roof on the ground, a flipped car and collapsed carports on her street.

“I’m thanking God,” she said. “Everyone ran outside in the rain, ignoring the quarantine, just trying to figure out if everyone was OK.”

Mayor James Mayo of Monroe and Ron Phillips, the director of Monroe Regional Airport, canceled all flights until further notice. Mr. Phillips told The News Star, a local newspaper, that the airport had about $30 million in damage.

Residents in Monroe, a city of more than 47,000, were warned to stay away from downed power lines and were asked to cooperate with emergency officials.

“We have downed power lines in many areas of Monroe,” Mr. Mayo said on the city’s Twitter account. “Monroe Fire & Police and repair crews are in various neighborhoods.”

In Ouachita, a parish nine miles southwest of Monroe, residents reported fallen trees and roof damage, said Glen Springfield, the public information officer at the Ouachita Parish Sheriff’s Office.

“There is some destruction to structures, but fortunately there are no reports of injuries in the parish,” Mr. Springfield said.

More strong tornadoes are likely through Monday morning for portions of northern and central Alabama and south-central Tennessee, according to the National Weather Service’s Storm Prediction Center. The service has issued severe thunderstorm warnings and a tornado watch for those areas.

“We expect large hail, destructive winds and tornadoes,” said Daniel Huckaby, a Weather Service meteorologist in Fort Worth. The hail could be larger than golf balls, and the winds could exceed 80 miles per hour, he said.

“This is not unusual this time of year in the South,” Mr. Huckaby said.

Warm and humid air flowing to the Deep South and strong winds are the perfect ingredients to produce severe weather, he said.

The storm cycle is expected to affect Georgia and the Carolinas by Monday morning.

“Everyone in the Deep South should keep alert and move to an interior room on the lowest floor,” Mr. Huckaby advised.

Parts of the Northeast are expected to face severe weather from a separate weather pattern on Monday, the National Weather Service said. The forecast suggested that parts of Suffolk County, on Long Island, and Middlesex County, Conn., could experience winds of up to 40 m.p.h. with gusts of up to 70 m.p.h.

Mariel Padilla and Aimee Ortiz contributed reporting.