City officials in Joplin, Mo., refused to give up hope of finding survivors even as the chances of finding people left alive by a vicious tornado dwindled by the hour.
"We are still in a search-and-rescue mode," Mark Rohr, Joplin's city manager said Wednesday. "I want to emphasize that."
The death toll from the massive twister that ripped clear across the Ozark Mountain town rose to at least 122 people. Hundreds of people were injured and at least nine people have been rescued from the debris.
Joplin Fire Commissioner Mitch Randles said he's still hopeful of finding survivors in the rubble as crews combed areas that had already been searched several times.
"We are searching every structure that's been destroyed in a more in-depth manner," he said.
Randles said dogs and dog handlers from across the country would also be participating in the search efforts.
The National Weather Service said the tornado was an EF5, the strongest rating assigned to tornadoes, with winds of more than 200 mph. Scientists said it appeared to be a rare "multivortex" tornado, with two or more small and intense centers of rotation orbiting the larger funnel.
Even as Joplin limped forward, a violent storm system had residents ducking for cover as sirens blared warnings overnight. The storms passed through without serious problems, but it spawned tornadoes and fierce winds that killed more than a dozen people as it raked Oklahoma, Arkansas and Kansas.
The rescue work in Joplin, a city of 50,000 people, was shadowed by uncertainty over just how many people remained to be found. News reports have claimed that hundreds of people remain missing, but local authorities hesitated to say how many are unaccounted for and said many people may have fled to safety and been unable to contact loved ones.
Social networks were the tool of choice for many people trying to track the missing or let friends and family know they were OK.
Several online efforts have focused on Will Norton, a teenager who vanished on his way home from his high school graduation ceremony. He was driving with his father when the storm hit his Hummer H3, which flipped several times. Will was thrown from the vehicle, likely through the sunroof.
His sister, Sara, was on the phone with her father and brother as the two were trying to drive home.
"I could hear him saying, 'Will, pull over, pull over,'" she said.
Mark Norton tried to grab his son, but the storm was too strong. He was hospitalized Tuesday, seriously hurt but still able to talk to his family about what happened.
Sara and other relatives drove to hospitals throughout Missouri to search for Will. More than 19,000 people supported the "Help Find Will Norton" community page on Facebook, and Twitter users were tweeting heavily about the missing teen.
"I just want to find him, that's all," Sara said Tuesday, on her way home from a hospital in Springfield, Mo. "I'm just determined. I have to find him."
Joplin schools were ravaged by the twister and classes have been canceled for the rest of the school year, but district officials are trying to locate both faculty and many of the school's 2,200 students. The effort has been crippled by downed phone lines. Some students have been located using Facebook.
"We just want to be able to find who we can find and then as confirmation happens offer support to the families if we find out that a kid didn't make it," Joplin High Principal Kerry Sachetta said.
"When a tragedy happens for a kid or a family, everybody tries to come together," Sanchetta said. "That's what we are trying to do a little piece at a time."
Meanwhile, structural engineers entered the battered Joplin hospital where the tornado killed five to see if the nine-story facility could be salvaged.
"It's truly was like a bomb went off almost on every floor," said Gary Pulsipher, chief executive at St. John's Regional Medical Center.
Lynn Britton, president and chief executive of Sisters of Mercy Health Systems, praised the "heroic" efforts by staff and others who helped in the storm's aftermath and said a temporary hospital would be running near the site by Sunday. Patient information was safe after the hospital moved from paper to electronic records in May.
Elsewhere in town, Michel Story stood in a pile of debris that was her grandmother's home, gazing at desolation stretching to the horizon.
"There's a lot of pain," she told NPR. "How can one thing do so much damage to one little town?"
In an old church converted into a community center, there was nothing left but a basement, battered by crumpled cars, full of sharp debris. Tiffany Story, clearly shaken, pointed to a door hanging ajar.
"This was the cast entrance," she said.
Motioning to her son, who was standing nearby, she said he was among the cast who hid in a stairwell. "It took everything I could do to hold him down," Story said as her voice quavered. "I almost lost him."
Two members of the cast died in the tornado. Others were badly hurt.
With reporting from NPR's Cheryl Corley and Frank Morris of member station KCUR. Material from The Associated Press was used in this story.