A child calls to his father after being pulled from the rubble of the Tower Plaza Elementary School.

Emergency workers pulled more than 100 survivors from the rubble of homes, schools and a hospital in an Oklahoma town hit by a powerful tornado, and officials lowered the death toll from the storm to 24, including nine children.

The two-mile (three-km) wide tornado tore through Moore outside Oklahoma City on Monday afternoon, trapping victims beneath the rubble, wiping out entire neighbourhoods and tossing vehicles about as if they were toys.

Seven of the nine children who were killed died at Plaza Towers Elementary School, which took a direct hit, but many more survived unhurt.

“They literally were lifting walls up and kids were coming out,” Oklahoma State Police Sergeant Jeremy Lewis said.

“They pulled kids out from under cinder blocks without a scratch on them.”

The Oklahoma state medical examiner’s office said 24 bodies had been recovered from the wreckage, down from the 51 they had reported earlier. The earlier number likely reflected some double-counted deaths, said Amy Elliott, chief administrative officer for the medical examiner.

“There was a lot of chaos,” she said.

Thunderstorms and lightning slowed the rescue effort on Tuesday, but 101 people had been pulled from the debris alive, Oklahoma Highway Patrol spokeswoman Betsy Randolph said, adding: “We are absolutely positive that there are still people that could be trapped under the rubble and in shelters.”

The National Guard and firefighters from more than a dozen fire departments as well as rescuers from other states worked all night under bright spotlights trying to find survivors.

President Barack Obama declared a major disaster area in Oklahoma, ordering federal aid to supplement state and local efforts in Moore after the deadliest US tornado since 161 people were killed in Joplin, Missouri, two years ago.

“The people of Moore should know that their country will remain on the ground, there for them, beside them, as long as it takes,” Obama said at the White House.

Glenn Lewis, the mayor of Moore, said the whole town looked like a debris field and there was a danger of electrocution and fire from downed power lines and broken natural gas lines.

“It looks like we have lost our hospital. I drove by there a while ago and it’s pretty much destroyed,” Lewis told NBC.

On Tuesday morning, a helicopter was circling overhead and thunder rumbled from a new storm as 35-year-old Moore resident Juan Dills and his family rummaged through the remains of what was once his mother’s home.

The foundation was laid bare, the roof ripped away and only one wall was still standing. They found a few family photo albums, but little else.

“We are still in shock,” he said. “But we will come through. We’re from Oklahoma.”

The National Weather Service assigned the twister a preliminary ranking of EF4 on the Enhanced Fujita Scale, meaning the second most powerful category of tornado with winds up to 200 mph (320 kph).