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Residents of Moore, Okla., started to return to their homes a day after a tornado smashed some neighborhoods into jagged wood scraps and gnarled pieces of metal. In place of their houses, many families found only empty lots.

Word that the tornado had been classified as the most devastating funnel cloud punch Mother Nature can deliver came as the death toll held steady at 24, including nine children.

The five ranking, on the Enhanced Fujita Scale, puts the tornado in the same class as the deadliest in U.S. history, which hit Joplin, Mo., in 2011, killing 158 and injuring hundreds more.

"An EF-5 is as bad as it gets," said Joe D'Aleo, co-chief forecaster for WeatherBell Analytics. "It's equivalent to a Category 5 hurricane. It means winds were more than 200 miles per hour, and it means you have to be underground, because there will be nothing left above ground."

Only 59 EF-5 tornadoes have touched down in the U.S. in the last 63 years, or just one-tenth of a percent of all tornadoes. Yet the most powerful of all twisters cause 20 percent of all tornado damage, and when they strike residential areas, they leave only rubble and misery in their wake. But a surprise revision downward of the death toll, which was initially reported at 51, and an outpouring of support from around the nation has left officials determined to heal.

"We will rebuild and we will regain our strength," said Oklahoma Gov. Mary Fallin, who went on a flyover of the area and described it as a “heartbreaking experience” that is "hard to look at."

Gary Bird, fire chief for the community of 56,000, said Tuesday afternoon he was "98 percent sure" there are no more survivors or bodies to recover under the rubble. His comments came after emergency crews spent much of the day searching the town's broken remnants for survivors of the twister that flattened homes and demolished an elementary school. Bird said his goal is to conduct three searches of each location that he was hopeful the work could be completed by nightfall.

No additional survivors or bodies have been found since Monday night, Bird said.

The Storm Prediction Center in Norman, Okla., forecast more stormy weather Tuesday in parts of Texas, Arkansas, Louisiana and Oklahoma, including the Moore, Okla., area where the tornado hit. The tornado, estimated to be up to two-miles wide, tore through Moore on Monday afternoon, a community of 41,000 people about 10 miles south of Oklahoma City.

Fallin said during a news conference Tuesday that many houses and buildings have been reduced to "sticks and bricks." Homes were seen crushed into piles of broken wood. Cars and trucks were left crumpled on the roadside. At least 38,000 in the area remain without power.

New search-and-rescue teams moved at dawn Tuesday, taking over from the 200 or so emergency responders who worked all night. A helicopter shined a spotlight from above to aid in the search.

The death toll of the storm was initially 51, but the Oklahoma City medical examiner's office downgraded it Tuesday to at least 24, saying some of the bodies may have been counted twice.

"To date, 24 deceased victims of the tornado have been transported to our Oklahoma City office, and positive identifications have been made in the vast majority of those, and these are ready for return to their loved ones," Elliott told FoxNews.com in an e-mail.

Nine of the bodies are children, seven of which were found at a school. Hospital officials say they've treated more than 200 patients, including more than 70 children.

“Our prayers are with the people of Oklahoma today,” President Barack Obama said in a Tuesday news conference, expressing gratitude for the residents and first responders who are assisting with the search and rescue efforts, and teachers who shielded their children as the tornado hit two schools.

“The people of Moore should know that their country will remain on the ground there for them, and be beside them as long as it takes,” Obama said. “Oklahoma needs to get everything that it needs right away.”

Fallin announced that the White House approved Oklahoma's request for disaster assistance for five counties: Cleveland, Lincoln, McClain, Oklahoma and Pottawatomie. Additional damage assessments could be added to the declaration.

Fallin also urged Oklahomans to call 1-800-621-FEMA for help, and said the state set up a website, www.okstrong.ok.gov, for information on available emergency services.

Many land lines to stricken areas were down after the tornado hit, and cellphone networks were congested. The storm was so massive that it will take time to establish communications between rescuers and state officials, Fallin said.

Crews continued their desperate search-and-rescue effort throughout the night at Plaza Towers Elementary, where the storm had ripped off the school's roof, knocked down walls and turned the playground into a mass of twisted plastic and metal as students and teachers huddled in hallways and bathrooms.

Children from the school were among the dead, but several students were pulled out alive earlier Monday from under a collapsed wall and other heaps of mangled debris. Rescue workers passed the survivors down a human chain of parents and neighborhood volunteers. Parents carried children in their arms to a triage center in the parking lot. Some of the students looked dazed while others appeared terrified.

James Rushing, who lives across the street from the school, heard reports of the approaching twister and ran to the school, where his 5-year-old foster son, Aiden, attends classes. Rushing believed he would be safer there.

“About two minutes after I got there, the school started coming apart,” he said.

As dusk fell, heavy equipment rolled up to the school, and emergency workers wearing yellow crawled among the ruins, searching for survivors. Crews used jackhammers and sledgehammers to tear away concrete, and chunks were being thrown to the side as the workers dug.

Douglas Sherman drove two blocks from his home to help.

”Just having those kids trapped in that school, that really turns the table on a lot of things, ” he said.

After hearing that the tornado was headed toward another school called Briarwood Elementary, David Wheeler left work and drove 100 mph through blinding rain and gusting wind to find his 8-year-old son, Gabriel. When he got to the school site, “it was like the earth was wiped clean, like the grass was just sheared off, ” Wheeler said.

Eventually, he found Gabriel, sitting with the teacher who had protected him. His back was cut and bruised and gravel was embedded in his head — but he was alive. As the tornado approached, students at Briarwood were initially sent to the halls, but a third-grade teacher — whom Wheeler identified as Julie Simon — thought it didn't look safe and so ushered the children into a closet, he said.

The teacher shielded Gabriel with her arms and held him down as the tornado collapsed the roof and starting lifting students upward with a pull so strong that it sucked the glasses off their faces, Wheeler said.

”She saved their lives by putting them in a closet and holding their heads down,” Wheeler said.

Families anxiously waited at nearby churches to hear if their loved ones had survived. A man with a megaphone stood Monday evening near St. Andrews United Methodist Church and called out the names of surviving children. Parents waited nearby, hoping to hear their sons' and daughters' names.

While some parents and children hugged each other as they reunited, others were left to wait, fearing the worst as the night dragged on.

Officials said one family with a baby tried to take shelter in a freezer, but did not survive, KFOR reports.

Pope Francis also expressed his condolences on his Twitter account.

“I am close to the families of all who died in the Oklahoma tornado, especially those who lost young children. Join me in praying for them,” he wrote.

"About two minutes after I got there, the school started coming apart."

— James Rushing, resident

In video of the storm, the dark funnel cloud could be seen marching slowly across the green landscape. As it churned through the community, the twister scattered shards of wood, awnings and glass all over the streets.

The tornado also destroyed the community hospital and some retail stores. Moore Mayor Glenn Lewis watched it pass through from his jewelry shop.

“All of my employees were in the vault,” Lewis said.

Chris Calvert saw the menacing cloud approaching from about a mile away.

“I was close enough to hear it,” he said. “It was just a low roar, and you could see the debris, like pieces of shingles and insulation and stuff like that, rotating around it.”

Even though his subdivision is a mile from the tornado's path, it was still covered with debris. He found a picture of a small girl on Santa Claus' lap in his yard.

A map provided by the National Weather Service showed that the storm began west of Newcastle and crossed the Canadian River into Oklahoma City's rural far southwestern side about 3 p.m Monday. When it reached Moore, the twister cut a path through the center of town before lifting back into the sky at Lake Stanley Draper.

The National Weather Service issued an initial finding that the tornado was an EF-4 on the enhanced Fujita scale, the second most-powerful type of twister. It also said the tornado was at least a half-mile wide, but other news reports estimated the width to be up to 2 miles.

Monday's powerful tornado loosely followed the path of a killer twister that slammed the region in May 1999; the storm then had winds clocked at 300 mph.

Kelsey Angle, a weather service meteorologist in Kansas City, Mo., said it's unusual for two such powerful tornadoes to track roughly the same path. It was the fourth tornado to hit Moore since 1998. A twister also struck in 2003.

Lewis, who was also mayor during the 1999 storm, said the city was already working to recover.

“We've already started printing the street signs,” he said. “It took 61 days to clean up after the 1999 tornado. We had a lot of help then. We've got a lot of help now.”

On Sunday, at least two people were killed and 29 were injured in Oklahoma as a severe storm system generated several tornadoes in Kansas, Oklahoma and Iowa, leveling neighborhoods and sending frightened residents scurrying for shelter.

At least four separate twisters touched down in central Oklahoma late Sunday afternoon, including one near the town of Shawnee, 35 miles southeast of Oklahoma City, that laid waste to much of a mobile home park.

Elliott on Monday said the two people killed in the Shawnee-area tornado were 79-year-old Glen Irish and 76-year-old Billy Hutchinson. Both men were from the town.

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The Associated Press contributed to this report.