The search for survivors and the dead is nearly complete in the Oklahoma City suburb that was smashed by a mammoth tornado, the fire chief said.
Gary Bird said he's "98 per cent sure" there are no more survivors or bodies to recover under the rubble in Moore, a community of 56,000 people.
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 a primary school. The storm killed at least 24 people, including at least nine children.
Every damaged home has been searched at least once, Bird said. His goal is to conduct three searches of each location just to be sure. He was hopeful the work could be completed by nightfall, but the efforts were being hampered by heavy rain.
No additional survivors or bodies have been found since Monday night (local time), Bird said.
Earlier in the day, the state medical examiner's office cut the estimated death toll by more than half.
Gov. Mary Fallin vowed to account for every resident.
"We will rebuild, and we will regain our strength," said Fallin, who went on a flyover of the area and described it as "hard to look at".
Amy Elliott, a spokeswoman for the medical examiner, said she believes some victims were counted twice in the early chaos of the storm that struck yesterday (NZT). Downed communication lines and problems sharing information with officers exacerbated the problem, she said.
"It was a very eventful night," Elliott said. "I truly expect that they'll find more today."
Authorities initially said as many as 51 people were dead, including 20 children.
New search-and-rescue teams moved in at dawn Tuesday (local time), taking over from the 200 or so emergency responders who had worked all night. A helicopter shined a spotlight from above to aid in the search.
Many houses have "just been taken away. They're just sticks and bricks," the governor said, describing the 27 kilometre path of destruction.
More than 200 people have been treated at hospitals.
The National Weather Service said the tornado was an EF5 twister, the most powerful type, with winds of at least 320 kph.
The agency upgraded the tornado from an EF4 on the enhanced Fujita scale to an EF5 based on what a damage-assessment team saw on the ground, spokeswoman Keli Pirtle said.
The weather service says the tornado's path was 27km long and 2km wide.
Emergency crews were having trouble navigating neighbourhoods because the devastation was so complete, and there are no street signs left standing, Fallin added.
Other search-and-rescue teams focused their efforts at Plaza Towers Elementary (primary), 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 neighbourhood volunteers. Parents carried children in their arms to a triage centre in the parking lot. Some students looked dazed, others terrified.
Officials were still trying to account for a handful of children not found at the school who may have gone home early with their parents, Bird said.
Many parents of missing schoolchildren initially came to St. Andrews United Methodist Church, which had been set up as a meeting site. But only high school students were brought to the church, causing confusion and frustration among parents of students enrolled at Plaza Towers. They were redirected to a Baptist church several miles away.
"It was very emotional - some people just holding on to each other, crying because they couldn't find a child; some people being angry and expressing it verbally" by shouting at one another, said D.A. Bennett, senior pastor at St. Andrews.
After hearing that the tornado was headed toward another school called Briarwood Elementary, David Wheeler left work and drove 160 kph 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.
The tornado also grazed a theatre and levelled countless homes. Authorities were still trying to determine the full scope of the damage.
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.
President Barack Obama declared a major disaster and ordered federal aid to supplement state and local recovery efforts.
"Among the victims were young children trying to take shelter in the safest place they knew - their school," he said.
The town of Moore "needs to get everything it needs right away," he added.
Obama spoke following a meeting with his disaster-response team, including Homeland Security Secretary Janet Napolitano and top White House officials.
The Storm Prediction Center in Norman, Okla., forecast more stormy weather in parts of Texas, Arkansas, Louisiana and Oklahoma, including the Moore area.
At the time of the storm, the City Council was meeting. Local leaders watched the twister approaching on television before taking shelter in the bathroom.
"We blew our sirens probably five or six times," Eddy said. "We knew it was going to be significant, and there were a lot of curse words flying."
THE 10 DEADLIEST US TORNADOES SINCE 1900:
• 695 deaths. March 18, 1925, in Missouri, Illinois and Indiana.
• 216 deaths. April 5, 1936, in Tupelo, Miss.
• 203 deaths. April 6, 1936, in Gainesville, Ga.
• 181 deaths. April 9, 1947, in Woodward, Okla.
• 158 deaths. May 22, 2011, in Joplin, Mo.
• 143 deaths. April 24, 1908, in Amite, La., and Purvis, Miss.
• 116 deaths. June 8, 1953, in Flint, Mich.
• 114 deaths. May 11, 1953 in Waco, Texas.
• 114 deaths. May 18, 1902 in Goliad, Texas.
• 103 deaths. March 23, 1913, in Omaha, Neb.
OKLAHOMA TORNADO TRACKED PATH OF 1999 TORNADO:
Today's powerful tornado in suburban Oklahoma City loosely followed the path of a killer twister that slammed the region in May 1999.
The National Weather Service estimated that the storm that struck Moore, Oklahoma, today had wind speeds of up to 320 kph, and was up to 1 kilometre wide. The 1999 storm had winds clocked at 480 kph, according to the weather service website, and it destroyed or damaged more than 8,000 homes, killing at least two people.
Kelsey Angle, a weather service meteorologist in Kansas City said it's unusual for two such powerful tornadoes to track roughly the same path. The 1999 twister was part of a two-day outbreak sweeping mostly across central Oklahoma - similar to the past two days.
The weather service has tentatively classified the Moore twister's wind speeds as an EF4 on a 5-point scale. Angle said less than 1 per cent of all tornadoes reach EF4 or EF5.
The thunderstorm developed in an area where warm moist air rose into cooler air. Winds in the area caused the storm to rotate, and that rotation promoted the development of a tornado. The most destructive and deadly tornadoes develop from rotating thunderstorms.
The biggest known tornado was nearly 4 kilometres wide at its peak width, which the weather service describes as near the maximum size for a tornado. It struck Hallam, Neb., in May 2004.
The deadliest tornado, which struck March 18, 1925, killed 695 people in Missouri, Illinois and Indiana.
Deaths from twisters have been declining in recent years because of improved forecasts and increased awareness by people living in tornado-prone areas, especially in smaller and rural communities.
TORNADOES IN NEW ZEALAND:
About 20 to 30 tornadoes happen in New Zealand each year, most frequently in the west and north. Tornadoes sometimes occur during thunderstorms, are sometimes preceded by a long, continuous roar or rumble, and generally last less than 15 minutes.
Damage paths are 10 to 20 metres wide and are usually less than five kilometres long.
WHAT TO DO:
• Develop a household emergency plan and prepare a portable getaway kit.
• When a warning is issued, alert others if possible.
• Take shelter in a basement or interior room without windows on the lowest floor, and get under sturdy furniture.
• Close windows, external and internal doors.
• Don't walk around outside, and avoid driving unless absolutely necessary.
• After the storm, listen to local radio stations for updates and advice from emergency management officials.
• Ask your council for advice on how to clean up debris safely.
Source: Ministry of Civil Defence and Emergency Management
- AP, AFP, AAP and APNZ