MOORE (Oklahoma) (Reuters) - 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.

The 3km-wide tornado tore through Moore outside Oklahoma City on Monday afternoon, trapping victims beneath the rubble.

Seven children 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.

Thunderstorms and lightning slowed the rescue effort on Tuesday, but 101 people had been pulled from the debris alive, Oklahoma highway patrol spokesman Betsy Randolph said.

At least 60 of the 240 people injured were children, hospital officials said.

Firefighters from more than a dozen fire departments and rescuers from other states worked all night under bright spotlights trying to find survivors.

Moore Mayor Glenn Lewis 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.