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At least six people were killed Sunday when tornadoes and severe windstorms plowed through Texas, Mississippi and other Southern states.

In Mississippi, the state's emergency management agency said three people in different counties near the Louisiana border — Walthall, Lawrence and Jefferson Davis — had died because of the weather.

The agency did not immediately provide more details, but the Lawrence County Sheriff's Office announced late Sunday night that one of its deputies, Robert Ainsworth, and his wife were among the dead.

"Robert left this world a hero, as he shielded Mrs. Paula during the tornado," the department said in a statement on its Facebook page. "He was a very valuable employee and will be greatly missed."

Robert Ainsworth, a United States Marine Corps veteran and longtime employee of the Lawrence County Sheriff's Office, was killed with his wife Paula during strong storms and tornadoes on Sunday, April 12, 2020. Lawrence County Sheriff's Office

The governors of Mississippi, Louisiana and Alabama each declared states of emergency to help recover from the damage caused by the storms.

Parts of central Texas were under tornado warnings Sunday morning as the twisters touched down accompanied by what witnesses called "gigantic" hail. Photos of the damage in Round Mountain, Texas, about an hour west of Austin, showed overturned trees and a trailer destroyed by the storm.

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Some customers in Central Texas were without power as officials worked to determine whether there were more than just two tornadoes, NBC affiliate KXAN of Austin reported.

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Extensive damage from severe windstorms was also reported in Monroe, Louisiana, a small city in the northern part of the state, while much of the southern region remained under tornado watches Sunday afternoon. Tornadoes have not yet been confirmed in the state by the National Weather Service.

City officials said on social media that trees and power lines had fallen throughout Monroe.

"We have downed power lines in many areas of Monroe. Do not touch or attempt to move them," Mayor Jamie Mayo said on Twitter.

All flights at Monroe Regional Airport were canceled until further notice, Director Ron Phillips said. The city posted pictures of the airport showing extensive damage and fallen debris.

Due to weather conditions and debris removal from the runways, Mayor Jamie Mayo and Monroe Regional Airport Director Ron Phillips announce “all flights at the Monroe Regional Airport are cancelled until further notice.” pic.twitter.com/Kw4zWNRtZT — City of Monroe, LA (@CityofMonroe) April 12, 2020

Gov. John Bel Edwards asked Louisiana residents to remain at home as severe weather continues through the state.

"Even though the morning storms have left the state, many other dangerous systems remain across Louisiana. Please stay at home, follow the orders of local officials and tune in to your local weather person for updates," he wrote on Twitter.

As of Sunday afternoon, no deaths have been reported in either state, and city officials in Monroe said a few people had suffered minor injuries.

The storms come as Louisiana remains one of the states hardest hit by the coronavirus pandemic, with over 20,000 cases as of Sunday, including more than 800 deaths. Texas had 12,561 reported cases, including 254 deaths.

New York Gov. Andrew Cuomo urged residents in the western region of the state to take precautions Sunday as they brace for a storm system that is expected to bring high winds and rains until Tuesday. Cuomo said the storm could cause flooding and power failures in the state hardest hit by the pandemic, with over 180,000 cases, including 8,627 deaths.

CORRECTION (April 12, 2020, 9:45 p.m. ET): An earlier version of this article misidentified the NBC affiliate in Austin, Texas. It is KXAN, not WXAN.