JOPLIN, Mo. --
The search for missing victims of Joplin's lethal twister inched forward methodically Wednesday, with city leaders refusing to abandon hope that they would find more survivors even as rescuers prepared to go over ground searched as many as three times already.
The death toll ticked upward to at least 122, with 750 people hurt, from a mighty twister that the National Weather Service said was an EF5, the strongest rating assigned to tornadoes, with winds of more than 200 mph.
"We are still in a search-and-rescue mode," said Mark Rohr, Joplin's city manager. "I want to emphasize that."
Even as Joplin limped forward, violent weather struck again, killing at least eight in Oklahoma, three in Arkansas and two more in Kansas. Late-night tornado sirens had Joplin's residents ducking for cover before the storm brushed past without serious problems.
Shadowing the rescue work in the southwest Missouri city of 50,000 people was uncertainty over just how many survivors remained to be found. Nine people have been rescued since Sunday's disaster, including two on Tuesday, but authorities have hesitated to say how many people are unaccounted for. They also said many were believed to have simply left the area safely.
Social networks were the tool of choice for many people trying to track the missing - or to let their loved ones 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. Norton was driving with his father, Mark Norton, when the storm hit his Hummer H3. The vehicle flipped several times, and Will was thrown from it, likely through the sunroof.
Sara Norton was on the phone with her father as the two drove home. Mark Norton asked her to open the family's garage door so Mark and Will could get inside quickly. But the two never made it.
I could hear him saying, `Will, pull over, pull over,'" Sara Norton 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.
Will's sister, Sara Norton, 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 Norton said Tuesday, on her way home from a Springfield, Mo., hospital. "I'm just determined. I have to find him."
Many posted prayers for Norton's safe return or repeated rumors about where he might have been taken. Others commented on videos that Norton, an avid videographer with plans to study film in college, had posted on YouTube.
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 and console everybody and make up what we can whether it is food or emotional support or a place to stay. That's what we are trying to do a little piece at a time."
The Joplin tornado was the deadliest single twister since the weather service began keeping official records in 1950 and the eighth-deadliest in U.S. history. Scientists said it appeared to be a rare "multivortex" tornado, with two or more small and intense centers of rotation orbiting the larger funnel.
Bill Davis, the lead forecaster on a National Weather Service survey team, said he would need to look at video to try to confirm that. But he said the strength of the tornado was evident from the many stout buildings that were damaged: St. John's Regional Medical Center, Franklin Technology Center, a bank gone except for its vault, a Pepsi bottling plant and "numerous, and I underscore numerous, well-built residential homes that were basically leveled."
Davis' first thought on arriving in town to do the survey, he said, was: "Where do you start?"
Heather Hollingsworth contributed to this story from Kansas City.