The death toll of the southern storms hit 345 today, making it the second deadliest twister outbreak in U.S. history, after the devastating storms of March 1925, when 747 people were killed in tornadoes that raged through Missouri, Illinois and Indiana.
Alabama was by far the hardest hit of the seven states in the storms' wake. In Alabama alone, already 1,700 people have been injured by the storms, according to Alabama Gov. Robert Bentley. The official state death toll hit 248, according to Alabama emergency officials.
The National Weather Service categorized Wednesday afternoon's tornado in Smithville, Miss., as an EF-5, reserved for only the fiercest and most devastating of tornadoes.
James LaDue, a meteorologist at the Warning Decision Training Branch, says EF-5s are worse than hurricanes and in terms of damage potential equal the tsunami that struck Japan in March.
"It is capable of completely sweeping away one- and two-story houses, leaving nothing left but the basement itself," LaDue said. "It's also capable of turning vehicles into missiles."
Since Wednesday, storms have ravaged communities across Alabama, Georgia, Mississippi, Kentucky, Virginia, Louisiana and Tennessee. At least 248 were killed in Alabama, 34 died in Mississippi, 34 in Tennessee, 15 in Georgia, five in Virginia, two in Louisiana and one in Kentucky.
The storms have destroyed or damaged power plants, power lines, gas stations and water supplies, leaving more than 1 million people without electricity. Thousands are homeless or without fuel or safe drinking water. Three nuclear power plants have shut down and are offline.
President Obama and the first lady toured the disaster area Friday in hard-hit Tuscaloosa, Ala., where 36 or more are dead. Eastern Tuscaloosa is running out of water. The mayor's office has ordered residents to conserve and to boil their tap water before drinking it until the city's water pressure can be fully restored.
Volunteers stepped in to help almost as soon as the storms passed through.
"I'm from the community, but my house wasn't damaged, so I had to help," Elsie Bailey, who was working in a room doling out men's clothing, told The Associated Press. "We were so amazed at the destruction that I just wanted to help. People are really stepping up, coming through."
Across the country, Americans have been donating to the relief effort, through text-message donations to the Red Cross and the Salvation Army, among other charities. The New York Yankees have donated $500,000 to relief efforts.
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Tales of Survival
For Jim and Sherryl Brewer, a quick trip to the Food Lion supermarket for a gallon of milk Wednesday in Ringgold, Ga., turned into a scene straight from the "Wizard of Oz."
As they pulled into the store's parking lot, the storm system that brought deadly twisters, soaking rains and damaging winds to the Southeast this week arrived.
"When I opened the door the first time, the wind just took it and wrapped it around. I knew then it was too late," Jim Brewer said.
Now stuck in their Toyota Forerunner, the couple tried to ride out the tornado.
"My husband put his arm through the steering wheel and grabbed hold of me," Sherryl Brewer said. "We just kind of held onto each other."
The twister shattered the car's windows and spun the car around, lifting its back end several times.
"We had glass in our hair. There was blood all over my hands and my legs. ... I've got little cuts where the glass went flying through the air," Sherryl Brewer said. "I don't think it lasted more than 15 seconds."
When the tornado moved on, the Brewers' car was on its side and the pair were pinned inside. Jim Brewer said they got out of the car through the sunroof after yelling for help.
"God was looking after us. There is a God. He took care of us," he said.
ABC News' Alan Farnham, Enjoli Francis and Yunji de Nies contributed to this report.