Joplin tornado breaks the records while new severe thunderstorm warnings are issued today.

 The tornado that struck Joplin, Missouri, Sunday killed 118 people, authorities said Tuesday, making it the deadliest single U.S. tornado since modern record-keeping began more than 60 years ago.

Missouri Gov. Jay Nixon said Tuesday morning the death toll has risen to 118 and the number of deaths is expected to rise as rescuers find more bodies in the rubble.

A twister in Flint, Michigan, in 1953 killed 116 people, according to the National Weather Service.

“It just looks like a war zone,” said Eddie Atwood in a CNN iReport from the scene. From where he stood, Atwood said, “You could see all the way to the horizon because all the houses and all the trees were just leveled.”

“I was walking down Main Street. Everything was so razed over, it was disorienting because some of the streets — you couldn’t even tell where you were at. After living in Joplin all my life it was like living in the twilight zone.”

Eleven of the deaths took place at the Greenbriar Nursing Home, according to the home’s vice president, Bill Mitchell. Ten residents and a staff member were killed by the tornado, and two other staffers are in critical condition at a hospital, Mitchell said.

Of the other 79 residents of the home, all but one are accounted for, he said. Survivors have been moved to temporary housing or are with family members.

President Barack Obama announced he will visit the region on Sunday. “We are going to do absolutely everything we can to make sure they recover,” he said, during a visit to London. Obama added that he will let people know “the whole country is going to be behind them.”

“We are here for you. We’re going to stay by you,” Obama said.

Richard Serino, the second-highest ranking official at the Federal Emergency Management Agency, said Obama has issued a disaster declaration — expediting the dispersal of federal resources to the area — while vowing that “we are going to be here for the long haul.”

Joplin may not be in the clear yet as far as weather goes: the National Weather Service warned there is a 45% chance of another tornado outbreak — with the peak time between 4 p.m. and midnight Tuesday — over a wide swath including parts of Texas, Oklahoma, Arkansas, Nebraska and Missouri. Officials in Joplin tested their tornado sirens at 10:30 a.m. local time (11:30 a.m. ET).

“There’s no way to figure out how to pick up the pieces as is,” Sarah Hale, a lifelong Joplin resident, said Tuesday. “We have to have faith the weather will change.”

“One, fortunately, walked away from it; the other one’s still in the hospital, last I heard,” Joplin Emergency Management Director Keith Stammer told CNN’s “American Morning.”

Several hundred people were injured in the tornado, and about 1,500 people are still unaccounted for, Stammer said. “What that means is they’ve scattered,” he said. “When we open up the area and starting letting them come back in… that number of unaccounted for will start to dwindle.”

People who have left the area should call their families and the dispatch center to let authorities know they are OK, Stammer said.

“We are hoping that by the time the sun goes down tonight, we’ll be done with our primary and our secondary search and rescue effort,” he added.

Joplin Fire Chief Mitch Randles said the second search basically follows the tornado’s path. “We’re searching every structure that’s been damaged or destroyed in a more in-depth manner,” he said. “The third search is going to be similar to that. And then the fourth search through will be with the search and rescue dogs.”

Authorities encouraged people to use the website safeandwell.org, operated by the Red Cross, for updates on loved ones.

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NEW THREAT EMERGES

Meanwhile a new severe thunderstorm threat is underway across the US.  Numerous states are affected, with the worst expected to peak over the next few hours.

– News by CNN, graphic by Weather.com