In South Carolina, Jason Matthews, 66, died Monday when strong winds flipped his mobile home several times, Union County Sheriff David Taylor said.
"He was barely alive when (his) brother found him. By the time EMS and law enforcement could get to him he had died from his injuries," Taylor said.
Earlier, in Florence, Mississippi, 52-year-old Jacqueline Williams was on the phone Monday morning with 911, trying to direct rescuers after her vehicle went off the road into a creek, Rankin County Coroner David Ruth said. She was unable to get out and died.
Greg Flynn with the Mississippi Emergency Management Agency said a tree fell Sunday night on a house in Glendora, killing a woman inside.
In Louisiana, 38-year-old Francine Gotch and her 3-year-old daughter Nevaeh Alexander, died Sunday when a tornado with winds of 100 mph blew their mobile home off its foundations in St. Martin Parish, the National Weather Service and local sheriff's office said.
The system that swept through Mississippi, Louisiana, Alabama and Georgia was bringing some rain and thunderstorms to the Carolinas on Monday evening. It was expected to continue moving north late Monday through Tuesday and could bring some rain to cities like Washington, Boston and New York.
Two new systems of storms are expected to emerge in Oklahoma and Louisiana on Tuesday, according to the National Weather Service Storm Prediction Center.
The storm system reached North Carolina late Monday afternoon, bringing heavy downpours.
Tornado watches issued for Charlotte, North Carolina, and about a dozen counties in North and South Carolina until 9 p.m. have been canceled, the National Weather Service said.
A two-hour ground stop for arriving aircraft at Charlotte Douglas International Airport was ordered by the Federal Aviation Administration, the airport tweeted.
Tornado warnings were issued for communities in west Georgia earlier in the day, and CNN affiliate WSB-TV reported two tornadoes touched down in Paulding County late Monday morning.
Afternoon practice for the Masters, the golf tournament in Augusta, was suspended, organizers said on Twitter.
Numerous trees were reported down in Carroll County, about 30 miles west of Atlanta, and a video posted on Twitter by WSB showed high winds ripping the roof off a fire station.
Georgia Power's website said nearly 18,000 customers remained without power as of 8 p.m. Monday. The Federal Aviation Administration ordered a ground stop on aircraft at Hartsfield-Jackson International Airport for about 30 minutes at midday, the airport tweeted.
The storm system raked Louisiana and Mississippi on Sunday, knocking out power in spots, causing evacuations and spinning off a deadly tornado.
At least three tornadoes were reported in northeast Louisiana, where 15 structures were damaged in Franklin Parish, said meteorologist Daniel Lamb of the National Weather Service's Jackson office.
In Rapides Parish in central Louisiana, rescuers pulled 250 people from single-family residences and a group home, said Sonya Wiley-Gremillion of the parish's Office of Homeland Security and Emergency Preparedness.
About 9,000 customers in the parish and the city of Alexandria lost power. Schools, including LSU Alexandria, were closed for the day Monday, she said.
In Mississippi, hundreds of people had to be rescued early Monday from their residences in Rankin County, outside Jackson, because of high water, reported CNN affiliate WLBT.
There also was flooding and wind damage in central Mississippi, with water rescues in the Vicksburg area, Lamb said.
He said the Big Black River was rising quickly in Mississippi's Bovina community and water had also entered homes around Pearl.
A tornado watch covered part of the Gulf Coast on Monday, including New Orleans and Mobile, said CNN meteorologist Dave Hennen. A severe thunderstorm watch covered much of central Alabama, including Montgomery, until noon.
There was a considerable threat of flash flooding from east Texas into Louisiana and Mississippi, CNN meteorologist Michael Guy said.
"Some areas have already seen over 5 inches with these severe storms (Sunday) in Louisiana, and the storms are slow moving. Rainfall could exceed up to another 3-6 inches locally in some areas causing flash flooding into the morning hours."