Communities across the South were on high alert Tuesday as a devastating storm system that left at least 34 people dead threatened to pack a one-two punch on the hardest-hit areas of Alabama and Mississippi.
The storm front killed at least 16 people on Monday when it slammed into parts of Alabama, Mississippi and Tennessee and produced more than 50 tornado reports in 24 hours.
A Mississippi coroner, Scott Gregory of Winston County, said he expected the death toll in that state to rise.
The storms spawned twisters, driving rain and scattered hail across swaths of the South and has been blamed for at least 18 deaths over the weekend in Arkansas, Oklahoma and Iowa.
On Tuesday, the areas hit hardest by severe weather “are going to get a repeat performance,” according to The Weather Channel's chief meteorologist, Kevin Roth. He said the severe storm that kicked off the chain of deadly tornadoes was so slow-moving that it’s “almost stationary.”
Roth warned that eastern Mississippi, eastern Tennessee and “all of Alabama” could be in line for a second hit — putting millions of people at risk.
“It is almost identical areas that are under the gun, two days in a row,” Roth said. “That’s not normally the case.”
Thousands hunkered down overnight in Alabama as tornado watches remained in effect and a state of emergency was declared.
Heavy damage was reported in Limestone County in the northern part of the state, the county emergency management agency told NBC News. At least two people were killed west of the town of Athens, according to Holly Hollman, a spokeswoman for the city.
Hollman said that at one point up to 16,000 people in the county were without power, but the number was decreasing. Trees and power lines are down across the county, she added.
The National Weather Service said the "large, violent" twister directly hit the Clements Fire Department shortly after 6 p.m. ET. The two victims were believed to have been in a mobile home park that was devastated.
The tornado caused major damage in Jefferson County city of Bessemer, Ala., with emergency officials reporting downed trees, gas leaks and power outages.
“We have not had any reports about injuries or fatalities so far but we’re still in the response phase,” said Horace Walker, spokesman for the Jefferson County's Emergency Management Agency. “It’s too early to give an idea about the extent of the damage.”
A "fairly significant" tornado flattened several homes in northeast Alabama's DeKalb County. Its emergency management agency's deputy director, Michael Posey, told NBC News downed trees and debris meant rescue crews could not reach victims.
Ben Luther, the county engineer at the DeKalb County Emergency Management Agency, said the process will take hours.
"All roads to the area have been cut off and we are probably looking at working through most of the morning and even the afternoon before we can get to them," he told NBC News. “And then we have got another round of storms coming today so we have to prepare for that, too.”
At midnight ET, a "supercell" storm system likely to spawn tornadoes was heading toward Birmingham and Jefferson County, the National Weather Service said. Tornado warnings also covered parts of Mississippi, where the death toll stood at seven from Monday’s tornado. Officials there, however, said they were still awaiting official confirmation to come Tuesday morning on the death toll.
Mississippi's emergency management agency said at least 16 counties reported tornado damage, with the full extent of the destruction unknown.
Parts of the state suffered extensive flooding, according to the National Weather Service, with some people trapped in their cars.
Mississippi Gov. Phil Bryant said the hardest-hit areas were Tupelo and Winston County near the town of Louisville.
"We're very fortunate that we have no reports of deaths in our city," Tupelo Mayor Jason Shelton said. North Mississippi Medical Center treated 24 people.
NBC station WTVA was live on the air when the tornado – described by the National Weather Service as “large and violent” – hit Tupelo, sending the news team scrambling.
Chief meteorologist Matt Laubhan shouted for staff to take cover, yelling “Basement, now!” in the dramatic footage.
Tennessee also took a hit when a tornado touched down in Lincoln County, near the Alabama line, and sent debris flying in the air. The National Weather Service said the twister was expected to cause “catastrophic damage" in parts of Lincoln and close-by Franklin and Moore counties.
Lincoln County Emergency Management confirmed two fatalities as a result of the tornadoes and widespread damage was reported.
"All of the southeastern side of Lincoln County has been hit and almost completely devastated," said Chelsea Bobo, a spokeswoman at the sheriff's office. "This is the worst this area has been hit in many years."