( CNN ) -- Once again , we confront the specter of a school day bathed in bloodshed . A 16-year-old , Alex Hribal , allegedly takes two long knives into a crowded corridor and sends 20 classmates and an adult to the hospital with grave injuries . Arraigned as an adult , Hribal looks all too familiar : thin , scared , vacant-eyed . He looks younger than his years as he is manacled and maneuvered into a police car . We have not yet filled in a motive . Hribal 's attorney says , `` He worked well in groups , and this happened . So there 's a reason for it -- that 's what I 'm saying . And we have to get to the bottom of that . '' And because it was knives , not guns , it was -- thankfully -- not a massacre . But much about the attack is familiar . Fifteen years ago , my doctoral students and I devoted two years to studying rampage shootings in American high schools in response to the epidemic epitomized by the 1999 Columbine High School shootings . To try to understand what motivates school attackers , we interviewed everyone who had any knowledge of two episodes -- one near Paducah , Kentucky , and the other outside Jonesboro , Arkansas -- that took place in the late '90s . Congress wanted to know about the circumstances that led to these outbursts in communities that have no experience of murderous violence . What we found at the center of the stories we followed were young men who looked a lot like Hribal . Rampage attacks happen in safe , relatively isolated communities . Indeed , they are most common in small rural towns where the biggest public `` stage '' is the local high school , the place the community gathers for events such as football games on Saturdays and everybody knows your name . The perpetrators are often described in the media as loners , but they are not . They are most often `` failed joiners , '' people who work overtime to ingratiate themselves into cliques that reject them . But they do n't stop trying . Fading into the background , close to anonymous , but rarely ever thought of as troublemakers , the protagonists look for ways to gain acceptance and attention . They may act like clowns ; they sometimes bully other children ; they steal -- all to seek the approval of social groups that continuously deny them recognition . In the instances we studied , all that effort starts to pay off the day they start talking about killing people . Suddenly they are the objects of attention . Everyone pivots toward them . They may even find their `` friends '' goading them . Michael Carneal , the shooter in Kentucky , resembled Hribal . Slight and short , he was a freshman who simply could not cut it in the world of high school peers . He was socially awkward and a bit of prankster , but he was n't a loner . Carneal tried to gain the friendship of many different social groups and finally landed in the laps of the Goths , boys who wore satanic garb and spoke in dark tones but who were actually among the smart ones . They told Carneal that the pistol he stole from home was n't good enough , that he should come to school in a trench coat sporting a shotgun . Carneal was so eager to gain their approval that he followed these instructions almost to the letter . Three kids huddled together in a prayer group were murdered , one was paralyzed from the waist down and a fifth was hit in the arms , her athletic career ended in an instant . But when Carneal shot these innocents , what was uppermost in his mind was not that he was going to kill kids but rather how this bold act would help him gain traction with the Goths . They would see him as notorious and dangerous rather than a loser who was awkward and boring . He told the forensic psychiatrist who interviewed him after his arrest that he had found a route to popularity . The Goths would visit his house and invite him to their homes . He would have friends once he proved himself worthy of their respect . We do n't know yet if the Murrysville , Pennsylvania , suspect fits this profile . The surprise that so many of his schoolmates have expressed comes close to what teachers told us about Carneal : that they could have named 50 others who might have committed this kind of mayhem before they got to him . The son of a lawyer and a homemaker , until the previous year a good student , with no obvious interest in guns , Carneal was not on their radar screen . But many teenagers avoided school on the Monday that Carneal murdered his classmates because they knew something bad was coming . One thing we should be grateful for : The attacker in Pennsylvania was armed only with knives . Had he had access to the weapons Carneal had , we would have seen dozens die rather than suffer these wounds . Knife attacks happen in countries such as Japan where guns are hard to access , and they have been lethal . Just not as deadly as a loaded high-capacity automatic weapon that requires a split second to gun down dozens of people . This is small comfort in Murrysville .
Katherine Newman has studied school rampages , says stabbing attack has echoes of them . She says they tend to happen in `` safe '' rural towns and suspects first mislabeled as loners . She says attackers often are `` failed joiners '' who seek acceptance in actions . They may have been bullied or teased at home. It 's small comfort for Pennsylvania town that attacker used knives instead of guns .