As rescue crews in this city made their way through the debris of thousands of homes and concrete slabs where large stores once stood, the death toll crept higher and a nursing home operator reported that at least 11 of the fatalities were at its premises.
"What used to be a building was nothing more than a pile of rubble," said Bill Mitchell, who operated Greenbriar on the city's south side. Ten victims were residents and the 11th was a staff member, he added. One person remains unaccounted for.
"One of the little old men from the nursing home was standing in the middle of the street when we came out of the house," neighbor Sandy Conlee told the Joplin Globe in describing the aftermath. "He had blood all over his head. He was in shock."
Conlee's brother and two sons went inside to search for survivors. "They said they wished they hadn't," she added. "There were bodies and broken bones and blood."
Staff at Greenbriar and another heavily damaged facility, Meadows Care Center, had received a warning that the storm was coming and started moving people into the halls. But it hit quicker than expected, Mitchell said.
More warning, he said, "wouldn't have mattered."
Greenbriar, which had 89 residents, and Meadows Care Center, which had 104, have been able to send survivors to other facilities.
The overall death toll rose Tuesday to 122, Joplin City Manager Mark Rohr said. He said more than 750 people were injured.
The twister was the deadliest single tornado to touch down in the U.S. since the National Weather Service began keeping official records in 1950, and the eighth-deadliest single twister in U.S. history.
The National Oceanic and Atmospheric Administration on Tuesday upgraded the Joplin tornado from EF-4 to EF-5, a category reserved for the fiercest and most devastating twisters. The agency said winds reached more than 200 mph.
Some 1,500 people were reported missing, according to Keith Stammer of Jasper County Emergency Management. That tally could include many who simply have not yet been able to let relatives know they are fine, authorities said.
The Joplin area was also bracing for new storms, after forecasters warned that a vast swath of the United States could be hit by severe thunderstorms — with a risk of tornadoes in Arkansas, Kansas, Oklahoma, Texas and Missouri, including Joplin.
Expect "a few strong tornadoes, very large hail and damaging winds over parts of the southern and central Plains and Ozarks this afternoon and tonight," the National Weather Service warned in a statement.
By midday, tornadoes had been reported on the ground near Canton, Okla., and Hugoton, Kan. A debris cloud was spotted outside Canton as the twister moved north.
In Joplin, search teams included one that poked through the remains of a Home Depot store, while others searched a Walmart and wrecked apartments as the clock ticked down on another round of severe storms that was forecast to hit later in the day.
Officials also tested nine tornado warning sirens while the sun was shining.
The Storm Prediction Center, a weather service division, said a repeat of the deadly April outbreak across the South could be setting up, with a possible large outbreak on Tuesday and bad weather potentially reaching the East Coast by Friday.
"This is a very serious situation brewing," center director Russell Schneider said.
The center cited a "moderate risk" of severe weather in central and southeast Kansas and southwestern Missouri, which could include Joplin. It raised the warning for severe weather in central Oklahoma, southern Kansas and north Texas to "high risk," indicating that tornadoes will hit in those areas.
The center also issued a high-risk warning before the deadly outbreak last month that killed 314 people across the South over two days.
Speaking from London, President Barack Obama said he would travel to Joplin on Sunday, and vowed to make all federal resources available.
"The American people are by your side," the president said. "We're going to stay there until every home is repaired, until every neighborhood is rebuilt, until every business is back on its feet."
FEMA Administrator Craig Fugate told NBC's TODAY that the agency is "here for the long haul."
Overnight, rescue crews worked through the rain-soaked chill, ignoring lightning and strong winds.
Two law enforcement officials were struck by lightning, one hurt very seriously, during violent thunderstorms on Monday.
Authorities fear the toll could rise as the full scope of the destruction comes into view: house after house reduced to slabs, cars crushed like soda cans, shaken residents roaming streets in search of missing family members.
Missouri Gov. Jay Nixon told NBC's TODAY show that Joplin faces a "long, sad and difficult" recovery — and that the number of dead likely "will move up."
Nixon said 17 people were found alive on Monday, although local officials confirmed only seven.
, said more storms were coming: "Sadly, given the events in Joplin, Mo., and Minneapolis this past weekend, we are not through with severe weather this week. Not by a long shot. The ingredients are in place for a classic Plains tornado outbreak Tuesday."
He said that atmospheric conditions were effectively creating a "cap" on the storm system, which — like putting a lid on a pot of boiling water increases the intensity of the boiling — was expected to result in "dangerous supercell thunderstorms" in the late afternoon or early evening Tuesday.
The Weather Channel produced a map, above, showing a vast area of the U.S. colored red, indicating areas where severe thunderstorms were possible and an even bigger area in orange where normal storms could hit.
Not since an April 1947 tornado in Woodward, Okla., had a single twister been so deadly. That storm killed 181 people, according to the National Weather Service.
"I've never seen such devastation — just block upon block upon block of homes just completely gone," said former state legislator Gary Burton who showed up to help at a volunteer center at Missouri Southern State University.
Hundreds were injured in this gritty, working-class town of 50,000 people about 160 miles south of Kansas City.
Roaring along a path nearly six miles long and up to 3/4 mile wide, the tornado flattened whole neighborhoods, splintered trees and flipped over cars and trucks.
The tornado destroyed possibly "thousands" of homes, said Fire Chief Mitch Randles. It leveled hundreds of businesses, including massive ones such as Home Depot and Walmart.
"We're getting sporadic calls of cries for help from rubble piles ... most of those are turning out to be false," Randles said.
Rescuers found one person alive at the Home Depot on Monday, but they also discovered seven bodies under a concrete slab, officials said.
Search-and-rescue team leader Doug Westhoff said team members have searched as much of the store's interior as they can and are now focused on what is under collapsed concrete slabs that once helped hold up the store. After the holes are drilled, dogs will be brought in to try to detect any human scent.
Among those missing was an 18-month-old boy who was separated from his parents when the twister hit. Hope was fading as the hours passed, said Chris Moreno, who was overseeing triage efforts outside St. John's Hospital, which was evacuated after suffering significant damage.
The boy was in a nearby home and Moreno said searchers feared his body was likely buried in a debris pile.
"We don't want a bulldozer to find the boy four months from now," Moreno said.
Joplin Mayor Mike Woolston told NBC's TODAY that he expects the search and rescue effort to continue at least through the day.
"Virtually every grid has been searched at least one time; several have been searched as many as three times. But we’ll continue that effort today to try to find those folks that we can. And probably search and rescue throughout the majority of the day, and then at the end of today we’ll take a look and at some point we’ll enter the recovery mode,” he said.
Some of the most startling damage was at St. John's Regional Medical Center, where staff had only moments to hustle their patients into the hallway. Six people died there, five of them patients, plus one visitor.
National Weather Service Director Jack Hayes said the tornado was given a preliminary label as an EF4 — the second-highest rating assigned to twisters based on the damage they cause.
Hayes said the tornado had winds of 190 to 198 mph.
'15 minutes of hell'As the tornado bore down on their trailer home, Joshua Wohlford, his pregnant girlfriend and their two toddlers fled to a Walmart store. The family narrowly escaped after a shelf of toys partially collapsed, forming a makeshift tent that shielded them.
"It was 15 minutes of hell," Wohlford said.
Evan Menke — a recent graduate of Joplin High School told NBC's TODAY that he and his family would be dead if a tree didn't fall on their car, anchoring it to the ground amid the swirling tornado.
"I told them to pull the car into the driveway and we were just engulfed in it. Glass was busting, our whole car got demolished," he said. "A tree fell on the hood and we think that if that didn't happen, we would be dead. We're very lucky to be alive."
At a Fast Trip convenience store, another 20 people ran into a pitch-black cooler as the building began to collapse around them.
They documented their experience with a video that was drawing tens of thousands of views online by Monday afternoon.
The audio was even more terrifying than the imagery — earsplitting wind, objects getting smashing, wailing children and a woman praying repeatedly.
Brennan Stebbins said the group crouched on the floor, clinging to and comforting each other until they were able to crawl out. No one was seriously hurt.
Dazed survivors tried to salvage clothes, furniture, family photos and financial records from their flattened or badly damaged homes.
The twister that hit Joplin was one of more than 50 reported across seven Midwest states over the weekend. One person was killed in Minneapolis and another in Kansas.