UPDATE: Death toll from severe storms at 35; 70 million remain under threat (w/ video)TUPELO, Mississippi (CNN) -- The scope is staggering. Some 75 million Americans are under threat of severe weather on Tuesday.
By: Ed Payne and Martin Savidge, CNN
The death toll from storms that struck Mississippi has climbed to 12, Greg Flynn of the Mississippi Emergency Management Agency told CNN on Tuesday. That brings the number of fatalities from the storm system that struck portions of the Midwest and South to 35.
70 million Americans under threat of severe weather
From Missouri to New York, Michigan to Florida, forecasters urged millions of Americans to keep an eye on the weather Tuesday, warning of tornadoes, high winds and hail spawned by the storm system that's killed 31 people in the last two days.
Roughly 70 million people are being warned of a slight to moderate risk of severe weather in the eastern half of the United States, according to the National Weather Service. That was a slight downgrade from an estimated 75 million people earlier in the day.
Mississippi and Alabama -- where tornadoes Monday caused widespread destruction and several deaths -- were again in the bull's-eye for the worst of Tuesday's forecast.
Tens of thousands were without power in those two states, where suspected tornadoes chewed through homes and businesses late Monday. At least 13 people were killed in Mississippi, Alabama and Tennessee on Monday. Those deaths are in addition to 18 others reported in Arkansas, Oklahoma and Iowa from storms Sunday.
In Tupelo, Mississippi, employees at a Steak Escape restaurant survived by huddling in the bathroom as the storm destroyed the building around them, Mayor Jason Shelton told CNN's "New Day."
"That was just a miracle of God," he said.
Anthony Bishop and his co-workers also had a close call when the storm hit their lube shop.
"Right as it ripped the roof off the building ... we all jumped in the pit," Bishop told CNN affiliate WMC-TV. "Heard blocks hitting cars above me, glass flying all around the pit where we were."
The National Weather Service's Storm Prediction Center said nearly 2.5 million people in parts of Alabama and Mississippi were at moderate risk of tornadoes, damaging winds and scattered large hail.
Risk areas stretched from the Great Lakes south to the Gulf of Mexico and east to the Atlantic Ocean.
The threat was expected to drift slowly east, putting parts of Florida, Georgia, the Carolinas and Mid-Atlantic states at a slight risk of severe weather Thursday, according to the Storm Prediction Center.
'It hurts to look'
Monday's storms left a trail of damage through several Mississippi and Alabama communities.
Mississippi authorities confirmed eight deaths there. Three people died in Alabama and two in Tennessee, according to officials.
Mississippi Gov. Phil Bryant said the twisters inflicted "severe damage" around the town of Louisville, about 90 miles northeast of Jackson.
Winston Medical Center, Louisville's major hospital, was among the buildings hit.
In Tupelo, buildings near a major commercial district on the city's north side were "wiped away," Scott Morris, a reporter for the Northeast Mississippi Daily Journal, told CNN's "The Lead."
Numerous trees and power lines were down, and "quite a few buildings are destroyed up there," Morris said.
The storm destroyed Britney Butler's home in Tupelo, WMC-TV reported.
"It hurts to look, because I won't come home tonight," said Butler, who still managed to smile after discovering her dog had come out unscathed. "Oreo means the most to me."
As things got ugly, Matt Laubhan, the chief meteorologist at Tupelo television station WTVA, took charge. He ordered station staff to take cover before walking off the set himself.
"Basement. Now ... let's go," Laubhan said.
Two people died in Lincoln County, Tennessee, near the border with Alabama.
Part of an elementary school there was torn away, the building's roof was ripped off and the storm hurled a school bus into the school, CNN affiliate WSMV reported. The bus and school were empty at the time, the station said.
Alabama also hit hard
One of the three Alabama deaths was a 21-year-old University of Alabama student from Tupelo, according to the school.
Jon Servati was a member of the school's swimming and diving team, the school's athletic department said in a statement. He died from injuries suffered at an off-campus home, the school said.
The other two deaths came at a trailer park near Athens, about 22 miles west of Huntsville.
The storm reduced a complex of houses and duplex apartments in the town to rubble. Downed power lines and gas leaks made the area dangerous, CNN's Brian Todd reported from Athens.
Authorities in Limestone County, where Athens is located, asked people to stay off roads wherever possible Tuesday. Emergency crews need unimpeded access to roads, and extensive damage and downed power lines make travel hazardous, authorities said in the message transmitted by the National Weather Service.
In Jefferson County, Alabama -- site of the state's largest city, Birmingham -- a fire station was hit, as was a church. People were trapped for a time in the church, but no one was seriously injured, Horace Walker, a spokesman for county's emergency management agency, told "New Day."
About 90,000 homes and businesses were without electricity Tuesday afternoon, according to Brian Corbett of the Alabama Emergency Management Agency. About 10,000 customers remained without power around Jackson, Mississippi, Entergy Mississippi reported.
Monday's storms were Act II of a powerful weather system that brought punishing thunderstorms to the central United States. Suspected tornadoes spawned by those storms on Sunday killed 15 people in Arkansas, two in Iowa and one in Oklahoma, authorities in those states reported.
Sunday's hardest-hit area was Faulkner County, Arkansas, where a suspected tornado shattered homes, tossed tractor-trailers and killed 11 people in the towns of Vilonia and Mayflower, including one death newly reported by authorities on Tuesday. Two children were among the dead.
CNN's Carma Hassan, Martin Savidge, Ed Payne, Chad Myers, Tina Burnside, Shawn Nottingham and Jill Martin contributed to this report.