US President Barack Obama travels to Joplin, Missouri, on Sunday to join grieving relatives in a memorial service for victims of one of the worst tornadoes ever to hit the United States as the death toll from the disaster rose to 142. The president and local residents, who planned to gather on the campus of Missouri Southern State University, were to observe a moment of silence exactly one week after the tornado cut a path of death and destruction through the heart of this town of 50,000. Among the newly confirmed killed by the tornado was teenager Will Norton, who was sucked by the wind out of his father\'s Hummer SUV as they drove home from his high school graduation. \"It\'s very disheartening,\" Joplin spokeswoman Lynn Onstot told AFP on Saturday. \"He was a high school senior who had just graduated. It was a very emotional story for everyone. It touched many of us.\" Crews continued searching for the missing, six days after the tornado tore apart everything it touched along a path four miles (six kilometers) long. There were 100 people still unaccounted for as early afternoon Saturday, the Missouri Department of Public Safety said in a statement. \"This number includes nine persons who have been reported deceased by family, but for whom official confirmation is still underway,\" the department said. Jasper County Coroner Ron Chappel pleaded for understanding from families angry that they were not being allowed to search for their missing loved ones among the dead at a temporary morgue. He said victims\' appearances are often altered in disasters like the one that struck Joplin, and so the coroner\'s office had to move carefully to avoid misidentifying the dead. But his office invited the public to provide photos of missing loved ones and information about scars, tattoos, piercings and other identifying marks. \"We are focused on the loss of the families and I want them to know that. It’s a traumatic process for us, for them, for all involved,\" Chappel said. State officials are cross-checking names of the missing with hospitals, and are working with cell phone service providers to determine if anyone has used their phone since being added to the list. The twister, a massive funnel cloud that struck late Sunday, ranks as the single deadliest tornado to hit the United States since modern record-keeping began in 1950. More than 8,000 structures in the Midwestern town, including a major commercial area, were damaged or destroyed when the tornado packing winds over 200 miles (320 kilometers) per hour came roaring through with just a 24-minute warning. Onstot said the city was slowly getting back on its feet, although the traditional Memorial Day weekend opening of Joplin\'s public pools has been postponed. \"Public transportation is back up and running, and trash is running as normal as possible,\" although not in the disaster areas, she added. Norton\'s family had been among those desperate to find their missing loved ones. Dozens of people had been helping his family search the debris field -- even heading out in a small plane to scan areas farther away. \"I\'m sorry to tell you that Will was found but he was not alive,\" his aunt Tracey Presslor posted on a Facebook page set up to organize search efforts that has garnered mass outpourings of support. \"We are grieving deeply. It brightens our lives to know that even in his passing he touched lives.\" She later added, in another post: \"People have lost their homes and their lives. Others are still missing and we cannot give up the search for them. Please keep praying for all of Joplin, Tuscaloosa and the other communities that are suffering.\" Sharyn Dawson has been searching for her 74-year-old mother-in-law, Patricia Dawson, whose apartment building was completely destroyed. As of Saturday, she was still listed as missing. Dawson said she can sympathize with the difficulty officials have faced in confirming the identities of the victims, but said it has left her with little choice but to keep looking until there is news. \"I don\'t want to jump on that bandwagon of people who have been screaming and yelling about how this process has worked. They don\'t understand how the process works. Neither do I,\" Dawson said. \"But I am almost to that place where I really want to know if she\'s in the morgue so I can quit wondering what happened.\" A total of 318 people are living in temporary shelters in Joplin, state officials said Saturday.