MOORE, Okla. - The tornado that tore through an Oklahoma City suburb destroyed or damaged as many as 13,000 homes and may have caused $2 billion in overall damage, officials said Wednesday.

State authorities meanwhile said two infants were among the 24 people who perished in the twister.

LOS ANGELES, Calif. - Blake Shelton and NBC are putting together a benefit for Oklahoma tornado victims.

Shelton told reporters about the fundraising effort after Tuesday night's episode of "The Voice." Shelton, an Oklahoma native, paid tribute to the thousands affected by Sunday and Monday's tornadoes by performing an acoustic version of the hit "Over You" with wife Miranda Lambert.

He said the benefit would be held soon in nearby Oklahoma City.

MOORE, Okla. - Rescue workers neared the end of the search for survivors and the dead in the Oklahoma City suburb where a mammoth tornado destroyed countless homes, cleared lots down to bare red earth and claimed 24 lives, including those of nine children.

MOORE, Okla. - The National Weather Service says the tornado that hit Moore, Okla., was a top-of-the-scale EF-5 twister with winds of at least 322 kilometres per hour.

Spokeswoman Keli Pirtle says the agency upgraded the tornado from an EF-4 on the enhanced Fujita scale to an EF-5 based on what a damage assessment team saw on the ground.

The weather service uses the word "incredible" to describe the power of EF-5 storms.

Authorities say 24 people, including nine children, were killed when the tornado flatted homes and demolished an elementary school on Monday.

MOORE, Okla. - The National Weather Service says the tornado that hit Moore, Oklahoma was a top-of-the-scale EF-5 twister with winds of at least 200 mph (322 kph).

Spokeswoman Keli Pirtle said Tuesday the agency upgraded the tornado from an EF-4 on the enhanced Fujita scale to an EF-5 based on what a damage assessment team saw on the ground. The weather service uses the word "incredible" to describe the power of EF-5 storms.

NASHVILLE, Tenn. - Tornadoes are a part of life in Moore, Oklahoma, something country star Toby Keith was reminded of when a deadly, devastating one levelled parts of his hometown on Monday.

"It's happened so many times through my life, I've been in so many," Keith said in a phone interview Tuesday. "During my life, probably on average every four or five years, you probably have one that's devastating. ... It affects you, somebody you know, every time."

MOORE, Okla. - The state medical examiner's office has revised the death toll from a tornado in an Oklahoma City suburb to 24 people, including seven children.

Spokeswoman Amy Elliot said Tuesday morning that she believes some victims were counted twice in the early chaos of the storm. Authorities said initially that as many as 51 people were dead, including 20 children.

Teams are continuing to search the rubble in Moore, south of Oklahoma City, after the Monday afternoon tornado.

MOORE, Okla. - As soon as I saw the tornado warnings on TV, I had to leave the office right away. I had photographed about a dozen tornados in my decade in Oklahoma and if I didn't get into my car before the funnel cloud swept through, I knew I would get stuck in traffic and arrive too late at the scene.

MOORE, Okla. - A monstrous tornado at least 800 metres wide roared through the Oklahoma City suburbs Monday, flattening entire neighbourhoods and destroying an elementary school with a direct blow as children and teachers huddled against winds of up to 320 kilometres an hour. At least 51 people were killed, including at least 20 children, and officials said the death toll was expected to rise.

MOORE, Okla. - The Oklahoma Medical Examiner's Office says the official death toll in the aftermath of a massive tornado that slammed the Oklahoma City area remains at 51 but is expected to rise.

Spokeswoman Amy Elliott told The Associated Press early Tuesday that officials could see as many as 40 more deaths from Monday's twister.