MURRYSVILLE, Pa. (AP) — Flailing away with two kitchen knives, a 16-year-old boy with a "blank expression" stabbed and slashed 21 students and a security guard in the crowded halls of his suburban Pittsburgh high school Wednesday before an assistant principal tackled him. 
 
 Alex Hribal, the suspect in the multiple stabbings at the Franklin Regional High School in Murrysville, Pa., is escorted by police to a district magistrate to be arraigned on Wednesday, April 9, 2014,... (Associated Press) 
 
 Alex Hribal, the suspect in the multiple stabbings at the Franklin Regional High School in Murrysville, Pa., is escorted by police to a district magistrate to be arraigned on Wednesday, April 9, 2014,... (Associated Press) 
 
 Westmoreland County emergency management spokesman Dan Stevens, left, looks on as Franklin Regional School District Superintendent Gennaro Piraino pauses while addressing the media during a news conference... (Associated Press) 
 
 A parent holds hands with a Franklin Regional High School while picking up the student after more than a dozen students were stabbed by a knife wielding suspect at the school on Wednesday, April 9, 2014,... (Associated Press) 
 
 Students walk past a row of buses as they leave the campus of the Franklin Regional School District after more then a dozen students were stabbed by a knife wielding suspect at nearby Franklin Regional... (Associated Press) 
 
 A man and woman walk away from Franklin Regional High School after more then a dozen students were stabbed by a knife wielding suspect at the school on Wednesday, April 9, 2014, in Murrysville, Pa., near... (Associated Press) 
 
 Students and guardians walk to their car from the Franklin Regional Middle School after more then a dozen students were stabbed by a knife wielding suspect at Franklin Regional High School on Wednesday,... (Associated Press) 
 
 Emergency responders gather in the parking lot of the high school on the campus of the Franklin Regional School District where several people were stabbed at Franklin Regional High School on Wednesday,... (Associated Press) 
 
 Students are escorted from the campus of the Franklin Regional School District after more then a dozen students were stabbed by a knife wielding suspect at nearby Franklin Regional High School on Wednesday,... (Associated Press) 
 
 Alex Hribal, the suspect in the multiple stabbings at the Franklin Regional High School in Murrysville, Pa., is escorted by police to a district magistrate to be arraigned on Wednesday, April 9, 2014,... (Associated Press) 
 
 A police officer guards the entrance Heritage Elementary School as students are dismissed after more than a dozen students were stabbed by a knife wielding suspect at nearby Franklin Regional High School... (Associated Press) 
 
 A student and guardian walk to their car from Franklin Regional Middle School after more then a dozen students were stabbed by a knife wielding suspect at nearby Franklin Regional High School on Wednesday,... (Associated Press) 
 
 Mike Kane, a parishioner at the Newlonsburg Presbyterian Church in Murrysville, Pa., works on a sign outside his church that abuts the Franklin Regional School District campus, where more then a dozen... (Associated Press) 
 
 Alex Hribal, the suspect in the multiple stabbings at the Franklin Regional High School in Murrysville, Pa., is escorted by police to a district magistrate to be arraigned on Wednesday, April 9, 2014,... (Associated Press) 
 
 Parents arrive to pick up their children from a nearby middle and elementary school after more then a dozen students were stabbed by a knife wielding suspect at Franklin Regional High School on Wednesday,... (Associated Press) 
 
 At least five students were critically wounded, including a boy whose liver was pierced by a knife thrust that narrowly missed his heart and aorta, doctors said. Others also suffered deep abdominal puncture wounds. 
 
 The rampage — which came after decades in which U.S. schools geared much of their emergency planning toward mass shootings, not stabbings — set off a screaming stampede, left blood on the floor and walls, and brought teachers rushing to help the victims. 
 
 Police shed little light on the motive. 
 
 The suspect, Alex Hribal, was taken into custody and treated for a minor hand wound, then was brought into court in shackles and a hospital gown and charged with four counts of attempted homicide and 21 counts of aggravated assault. He was jailed without bail, and authorities said he would be prosecuted as an adult. 
 
 His attorney did not immediately respond to a message for comment. 
 
 The attack unfolded in the morning just minutes before the start of classes at 1,200-student Franklin Regional High School, in an upper-middle-class area 15 miles east of Pittsburgh. It was over in about five minutes, during which the boy ran wildly down about 200 feet of hallway, slashing away with knives about 8 to 10 inches long, police said. 
 
 Nate Moore, 15, said he saw the boy tackle and stab a freshman. He said he going to try to break it up when the boy got up and slashed his face, opening a wound that required 11 stitches. 
 
 "It was really fast. It felt like he hit me with a wet rag because I felt the blood splash on my face. It spurted up on my forehead," he said. 
 
 The attacker "had the same expression on his face that he has every day, which was the freakiest part," Moore said. "He wasn't saying anything. He didn't have any anger on his face. It was just a blank expression." 
 
 Assistant Principal Sam King finally tackled the boy and disarmed him, and a Murrysville police officer who is regularly assigned to the school handcuffed him, police said. 
 
 King's son told The Associated Press that his father was treated at a hospital, though authorities have said he did not suffer any knife wounds. 
 
 "He says he's OK. He's a tough cookie and sometimes hides things, but I believe he's OK," Zack King said. He added: "I'm proud of him." 
 
 In addition to the 22 who were stabbed or slashed, two people suffered other injuries during the melee, authorities said. The security guard, who was wounded after intervening early in the melee, was treated and released. 
 
 "There are a number of heroes in this day. Many of them are students," Gov. Tom Corbett said in a visit to the stricken town. "Students who stayed with their friends and didn't leave their friends." 
 
 As for what set off the attack, Murrysville Police Chief Thomas Seefeld said investigators were looking into reports of a threatening phone call between the suspect and another student the night before. Seefeld didn't specify whether the suspect received or made the call. 
 
 The FBI joined the investigation and went to the boy's house, where authorities said they planned to confiscate and search his computer. 
 
 "They are a very, very nice family. A great family. We never saw anything out of the ordinary," said John Kukalis, a next-door neighbor for about 13 years. 
 
 His wife, Sonya Kukalis, said: "It should be an eye-opener for everybody. Everyone always thinks it's the other neighborhood, the other town. We need to be kinder and show compassion to more people. Something must have been going on for him to do this." 
 
 While several bloody stabbing rampages at schools in China have made headlines in the past few years, schools in the U.S. have concentrated their emergency preparations on shooting rampages. 
 
 Nevertheless, there have been at least two major stabbing attacks at U.S. schools over the past year, one at a community college in Texas last April that wounded at least 14 people, and another, also in Texas, that killed a 17-year-old student and injured three others at a high school in September. 
 
 On Wednesday, Mia Meixner, 16, said the rampage touched off a "stampede of kids" yelling, "Run! Get out of here! Someone has a knife!" 
 
 The boy had a "blank look," she said. "He was just kind of looking like he always does, not smiling, not scowling or frowning." 
 
 Meixner and Moore called the attacker a shy boy who largely kept to himself, but they said he was not an outcast and they had no reason to think he might be violent. 
 
 "He was never mean to anyone, and I never saw people be mean to him," Meixner said. "I never saw him with a particular group of friends." 
 
 Michael Float, 18, said he had just gotten to school when he saw "blood all over the floor" and smeared on the wall near the main entrance. Then he saw a wounded student. 
 
 "He had his shirt pulled up and he was screaming, 'Help! Help!'" Float said. "He had a stab wound right at the top right of his stomach, blood pouring down." 
 
 Float said he saw a teacher applying pressure to the wound of another student. 
 
 About five minutes elapsed between the time the campus police officer summoned help over the radio at 7:13 a.m. and the boy was disarmed, the police chief said. 
 
 Someone, possibly a student, pulled a fire alarm during the attack, Seefeld said. Although that created chaos, the police chief said, it emptied out the school more quickly, and "that was a good thing that that was done." 
 
 Also, a girl with "an amazing amount of composure" applied pressure to a schoolmate's wounds and probably kept the victim from bleeding to death, said Dr. Mark Rubino at Forbes Regional Medical Center. 
 
 Public safety and school officials said an emergency plan worked as well as could be expected. The district conducted an emergency exercise three months ago and a full-scale drill about a year ago. 
 
 "We haven't lost a life, and I think that's what we have to keep in mind," said county public safety spokesman Dan Stevens. 
 
 ___ 
 
 Associated Press writers Mike Rubinkam in Allentown and Jesse Washington in Murrysville, Pa., and AP news researchers Judith Ausuebel and Barbara Sambriski contributed to this report. ||||| Story highlights The DA says 4 people are in critical condition, including one who was "eviscerated" 
 
 Alex Hribal, 16, faces 4 counts of attempted homicide, 21 counts of aggravated assault 
 
 Teachers use students' hoodies as tourniquets on injured teens, student says 
 
 An assistant principal tackled the accused attacker, authorities say 
 
 A teenage boy wielding two kitchen knives went on a stabbing rampage at his high school in Murrysville, Pennsylvania, early Wednesday, before being tackled by an assistant principal, authorities said. 
 
 Twenty students and a security officer at Franklin Regional Senior High School were either stabbed or slashed in the attack, Westmoreland County District Attorney John Peck told reporters. 
 
 The accused attacker was been identified as 16-year-old Alex Hribal, according to a criminal complaint made public. Hribal, who was arraigned as an adult, faces four counts of attempted homicide, 21 counts of aggravated assault and one count of possession of a weapon on school grounds, the documents show. 
 
 "I'm not sure he knows what he did, quite frankly," Hribal's attorney, Patrick Thomassey, said, adding he would file a motion to move the case to juvenile court. 
 
 "...We have to make sure that he understands the nature of the charges and what's going on here. It's important that he be examined by a psychiatrist and determined where he is mentally." 
 
 A doctor who treated six of the victims, primarily teens, said at first they did not know they had been stabbed. 
 
 "They just felt pain and noticed they were bleeding," Dr. Timothy VanFleet, chief of emergency medicine at the University of Pittsburgh Medical Center, told CNN. 
 
 "Almost all of them said they didn't see anyone coming at them. It apparently was a crowded hallway and they were going about their business, and then just felt pain and started bleeding." 
 
 Arguing against bail for Hribal, the district attorney told the court that four of the victims were in critical condition, including one who was "eviscerated." There's a question whether the victim will survive, Peck said. 
 
 Hribal is being held without bail at the Westmoreland County juvenile detention center. 
 
 Authorities have not detailed a possible motive in the attack, but the district attorney said in court the teen made "statements when subdued by officials that he wanted to die." 
 
 'Don't know what I got going down' 
 
 The carnage began shortly before the start of classes, when an attacker began stabbing students in a crowded hallway and then went from classroom to classroom. 
 
 Student Matt DeCesare was outside the school when he heard a fire alarm ring and then saw two students come out of the school covered in blood. 
 
 Then he saw teachers running into the building and pulling "a couple of more students out," he told CNN. The students had been stabbed. 
 
 To stanch the bleeding, the teachers asked the students for their hoodies. 
 
 "We all took our hoodies off and handed them to the teachers to use as tourniquets to stop the bleeding," he said. 
 
 Recordings of emergency calls released in the wake of the attack provide a soundtrack of sorts to the terror and chaos that played out inside the school. 
 
 "I don't know what I got going down at school here but I need some units here ASAP," one officer can be heard saying. 
 
 Minutes later in another call, another official, breathlessly, can be heard detailing casualties: "About 14 patients right now." 
 
 Then another call for help. "Be advised inside the school we have multiple stab victims," one of the officers said. "So bring in EMS from wherever you can get them. 
 
 'Saw the kid who was stabbing people' 
 
 Student Mia Meixner was standing at her locker. 
 
 "I heard a big commotion like behind my back," she told CNN. "And I turned around and I saw two kids on the ground." 
 
 She thought a fight had broken out, but then she saw blood. 
 
 "I saw the kid who was stabbing people get up and run away," she said. 
 
 Then she saw a girl she knew standing by the cafeteria. "She was gushing blood down her arm." 
 
 Meixner dropped her books and went to help the girl. 
 
 "I started hearing a stampede of students coming down from the other end of the hall, saying 'Get out, we need to leave, go, there's a kid with a knife.' Then a teacher came over to me and the girl I was trying to help. And she said she would handle the girl and that I should run out. So then I just ran out of the school and tried to get out as soon as possible." 
 
 Meixner never heard the attacker utter a word. 
 
 "He was very quiet. He just was kind of doing it," she said. "And he had this, like, look on his face that he was just crazy and he was just running around just stabbing whoever was in his way." 
 
 She said she didn't know the boy, but he had been in a lot of her classes. "He kept to himself a lot," she said. "He didn't have that many friends that I know of, but I also don't know of him getting bullied that much. I actually never heard of him getting bullied. He just was kind of shy and didn't talk to many people." 
 
 Hribal's attorney described him as a "nice young man," who has never been in trouble. 
 
 "He's not a loner. He works well with other kids," he said. "...He's scared. He's a young kid. He's 16, looks like he's 12. I mean, he's a very young kid and he's never been in trouble so this is all new to him." 
 
 At least a dozen FBI agents could be seen going in and out of Hribal's family home in the hours after the attack. Shortly before the agents arrived at the house, a man believed to be Hribal's father drove up. 
 
 "My prayers go out to everyone who was injured today, and I hope they recover as soon as possible," he told reporters. 
 
 Hribal's attorney said the family was upset by the allegations. "They did not foresee this at all," he said. 
 
 Tackled by an assistant principal 
 
 Assistant Principal Sam King is being credited with bringing to an end the 5-minute rampage that authorities say began about 7:15 a.m. ET. 
 
 King tackled the teen, Peck told reporters. A school resource officer was able to handcuff the suspect, Police Chief Thomas Seefeld said. 
 
 The accused teen was being treated for injuries to his hands, the chief said. 
 
 Police Officer William "Buzz" Yakshe, who also serves as a resource officer at the school, helped subdue the suspect, said Dan Stevens, the county deputy emergency management coordinator. Yakshe is "doing fine," Stevens said. "He's more upset than anything else over what happened, because these are his kids." 
 
 A fire alarm that was pulled during the attack probably helped get more people out of the school during an evacuation order, Seefeld said. Students were running everywhere and there was "chaos and panic." 
 
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 Photos: Stabbings at Pennsylvania high school Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – Parents and students embrace near Franklin Regional High School, where authorities say at least 20 people were injured in a stabbing spree Wednesday, April 9, in Murrysville, Pennsylvania. Hide Caption 1 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – Accused attacker Alex Hribal, 16, is escorted from a district magistrate after he was arraigned as an adult on April 9. He faces four counts of attempted homicide, 21 counts of aggravated assault and one count of possession of a weapon on school grounds, according to a criminal complaint made public. Hide Caption 2 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – A police officer blocks the entrance to the school on April 9. Hide Caption 3 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – Students leave the school's campus on April 9. Hide Caption 4 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – A police officer stands by the scene outside the high school on April 9. Hide Caption 5 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – A woman walks onto the campus of the Franklin Regional School District on April 9. Hide Caption 6 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – Students walk away from the campus on April 9. Hide Caption 7 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – Emergency responders gather in the parking lot of Franklin Regional High School on April 9. Hide Caption 8 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – Jenna Mickel, a sophomore at Franklin Regional High School, stands with her father, Richard, as she talks to reporters outside the school on April 9. Hide Caption 9 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – Emergency responders gather in the high school's parking lot. Hide Caption 10 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – A pair of women leave the school's campus on April 9. Hide Caption 11 of 12 Photos: Stabbings at Pennsylvania high school Stabbings at Pennsylvania high school – A Salvation Army disaster services vehicle drives past a school bus and onto the campus on April 9. Hide Caption 12 of 12 
 
 At one point, a female student applied pressure to the wounds of one of the male victims, possibly helping to save his life, said Dr. Mark Rubino, chief medical officer at Forbes Regional Hospital in nearby Monroeville, Pennsylvania, where seven teens were taken for treatment. 
 
 The students who were hurt range in age from 14 to 17, Stevens said. The injuries were stabbing-related, such as lacerations or punctures, he said. 
 
 'It doesn't happen here' 
 
 The attack in Murrysville is the latest in a string of school violence that has occurred across the nation. But mass stabbings, such as the one at the high school, are rare. 
 
 The attack has rattled the town, a residential enclave with a population of about 20,000. 
 
 A message on the Franklin Regional School District's website said all of its elementary schools were closed after the incident, and "the middle school and high school students are secure." 
 
 Franklin Regional Senior High will be closed "over the next several days," district school Superintendent Gennaro Piraino said. The district's middle school and elementary schools will be open Thursday, and counseling will be available for the whole district, he said. 
 
 Information on what led to the stabbings and the conditions of the injured are still unfolding. 
 
 Bill Rehkopf, a KDKA radio host and Franklin Regional High School graduate, called the stabbing shocking. 
 
 He said he kept thinking, "It doesn't happen here, it can't happen here."
– A student who was stabbed in the liver remains in critical condition following today's rampage at a high school in suburban Pittsburgh that left 23 others injured and a sophomore in custody. The suspect is 16-year-old Alex Hribal, and he has been charged as an adult with four counts of attempted homicide and 21 counts of aggravated assault. The motive remains unclear, but the AP says police are investigating reports of a threatening phone call between Hribal and another student last night. It wasn't clear which of the two made the call. The accounts of exactly what happened at Franklin Regional High School in Murrysville are still unfolding, but authorities say assistant principal Sam King and a security guard at the school tackled and subdued the attacker in a hallway. Some other details emerging: The attack began in a classroom when Hribal pulled out two 8-inch kitchen knives and began slashing students, reports the Pittsburgh Post-Gazette. He reportedly followed them as they fled into the hallway and stabbed others as he ran. During the assault, the attacker "was very quiet," student Mia Meixner tells CNN. "He just was kind of doing it. And he had this, like, look on his face that he was just crazy and he was just running around just stabbing whoever was in his way." A doctor at a nearby hospital said a female student with "an amazing amount of composure" likely saved the life of one of the more seriously injured male students by applying pressure to his wounds. That appears to be junior Gracie Evans, who recounts to the Pittsburgh newspaper: "My friend was on his stomach, and the other kid who was severely injured was told to sit up. I knew that wasn't right. I said to a few students, we need pressure on this wound, and they gave me some paper towels, and I held pressure on that wound for about 10 minutes." Authorities say 22 people were stabbed or slashed, all but one of them students, and two more students suffered other injuries in the chaos.