MOORE, Oklahoma - The search for survivors and the dead was nearly complete Tuesday in the broken remnants of an Oklahoma City suburb where a massive tornado flattened homes and demolished an elementary school, the fire chief said. Authorities lowered the death toll to 24, down from 51.

Fire Chief Gary Bird said that he's "98 percent sure" there are no more survivors or bodies to recover under the rubble in the town of Moore. He said every damaged home had been searched at least once and that he's hopeful the work could be completed by nightfall Tuesday, though heavy rains slowed efforts.

Resident Taylor Tennyson sits in the front yard as family members salvage the remains from their home which was left devastated by a tornado in Moore, Oklahoma, in the outskirts of Oklahoma City May 21, 2013. [Photo/Agencies]

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

Authorities initially reported a higher death toll because some victims were apparently counted twice in the early chaos of the storm, said Amy Elliot, a spokeswoman for the state medical examiner's office. Downed communication lines and problems sharing information with officers exacerbated the problem, she said.

The death toll included at least nine children. More than 200 people were treated at area hospitals.

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

The ferocious storm, clocking winds of up to 200 mph (320 kph), reduced homes to piles of splintered wood in Moore, a town in a central US region known as Tornado Alley. Less than 1 percent of all tornadoes reach such wind speed.

The National Weather Service said the tornado was an EF-5 on the enhanced Fujita scale, the most powerful type of twister. It was the first EF-5 tornado of 2013, said spokeswoman Keli Pirtle.

In Washington, President Barack Obama pledged urgent government help.

"In an instant, neighborhoods were destroyed, dozens of people lost their lives, many more were injured," Obama said. "Among the victims were young children trying to take shelter in the safest place they knew their school."

The storm left scores of blocks barren and dark in Moore, a community of 41,000 people 10 miles (16 kilometers) south of Oklahoma City.

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.

Other search-and-rescue teams focused their efforts at Plaza Towers Elementary, where the storm ripped off the 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.

Seven of the nine dead children were killed at the school, but several students were pulled alive 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 students looked dazed, others terrified.

After hearing that the tornado was headed toward another school called Briarwood Elementary, David Wheeler left work and drove 100 mph (160 kph) through blinding rain and gusting wind to find his 8-year-old son, Gabriel. When he got there, "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.

Oklahoma has reinforced tornado shelters in more than 100 schools across the state, but the two that were in Moore did not have them, said Albert Ashwood, director of the Oklahoma Department of Emergency Management. He said a shelter would not necessarily have saved more lives at Plaza Towers Elementary.

Authorities were still trying to determine the full scope of the damage.  The weather service said the tornado's path was 17 miles (27 kilometers) long and 1.3 miles (2 kilometers) wide.

U.N. Secretary General Ban Ki-moon wrote to the Oklahoma governor to express his condolences and offer the assistance of the United Nations, if requested, said U.N. deputy spokesman Eduardo del Buey.

Roofs were torn off houses, exposing metal rods left twisted like pretzels. Cars sat in heaps, crumpled and sprayed with caked-on mud. Insulation and siding was smashed up against the sides of any walls that remained standing. Yards were littered with pieces of wood, nails and pieces of electric poles.

Monday's twister also came almost exactly two years after an enormous twister ripped through the city of Joplin, Missouri, killing 158 people.

That May 22, 2011, tornado was the deadliest in the United States since modern tornado record keeping began in 1950, according to the National Oceanic and Atmospheric Administration.