The massive storm system that killed several people from Texas to Mississippi is now barreling east, threatening to spawn tornadoes and other catastrophic weather from New England to the Gulf Coast.
About 90 million people are under the gun for destructive weather Sunday, CNN meteorologist Haley Brink said.
While Sunday's storms might not be as severe as the ones that battered the South on Saturday, they will hit far more people in heavily populated cities.
"New York, Washington DC and Atlanta all within the zone," CNN Meteorologist Derek Van Dam said.
At least one tornado was reported Sunday morning in southeast Alabama, near Troy and Goshen, the National Weather Service's Birmingham office said.
"Heavy rainfall may hide this tornado. Do not wait to see or hear the tornado. Take cover now," the NWS office said.
"Flying debris will be dangerous to those caught without shelter. Mobile homes will be damaged or destroyed. Damage to roofs, windows, and vehicles will occur. Tree damage is likely."
Not just tornadoes
But tornadoes aren't the only possible cause of destruction Sunday.
"Damaging winds and some hail are also associated with these storms pushing through the Southeast this morning," Brink said.
The threat of severe weather will likely increase throughout the day, the National Weather Service's Storm Prediction Center said.
"Some storms may also produce large hail or torrential downpours resulting in localized flash flooding," the weather service tweeted.
At least 3 children killed in this storm system
The storm system's first two victims were two children in east Texas.
The children, ages 3 and 8, were killed when a tree fell on a car. They were in the back seat with their parents in the front, Angelina County Sheriff's Department Capt. Alton Lenderman said.
A preliminary damage survey showed an EF-3 tornado, with winds up to 140 mph, touched down in Robertson County, the NWS in Fort Worth said.
Multiple injuries were reported in the Robertson County town of Franklin, the NWS said. CNN affiliate KWTX reported widespread damage there, including uprooted trees and roofs ripped off buildings.
The entire town of Franklin and neighboring Bremond lost electricity, with 3,088 customers without power early Sunday.
About two hours north of Franklin, dime-sized hail pelted the Dallas-Fort Worth area.
The rash of storms then headed east, where it claimed the life of a Louisiana teen. The 13-year-old boy drowned in a drainage area in West Monroe late Saturday afternoon, the Ouachita Parish Sheriff's Office said. The death is believed to be storm related, the sheriff's office said.
'We are just a mess'
Warm air enhanced the atmosphere's instability Saturday, allowing the storm system to rev up more energy and grow, CNN meteorologist Chad Myers said.
But "the storm is so vigorous that tornadoes are still possible after dark," he said.
As the storms tore through Mississippi overnight into Sunday, they left a trail of destruction that authorities are still combing through.
It's still not clear how many lives this storm system has claimed. On Sunday, the Mississippi Emergency Management Agency said multiple fatalities have been confirmed in Monroe County, but did not say how many.
The fire station in Hamilton was destroyed, as were multiple homes and a retail center.
"It looks like a storm came up through Louisiana and into Mississippi and exploded in Monroe County," Monroe County Sheriff Cecil Cantrell said.
"We were hit really, really, hard. We have a lot of flooding. There are several trees down. We are just a mess."
Famed golf tournament rushes to finish
At Georgia's Augusta National Golf Club, organizers of The Masters golf tournament moved up tee times Sunday to try to beat dangerous weather.
Storms are expected to move through the Augusta area Sunday afternoon and evening.
While the threat of tornadoes will be lower by then, damaging winds could still bring perilous conditions.