A student flashing two knives went on a stabbing and slashing rampage at a high school near the American city of Pittsburgh yesterday, leaving as many as 20 people injured, including four students who suffered serious wounds.
A witness said the male suspect was tackled by assistant principal Sam King. The 16-year-old was taken into custody and was being questioned by police. All the victims were expected to survive, doctors said.
Not all of the 20 injured at Franklin Regional High School were cut by the knives, though most were, Westmoreland County emergency management spokesman Dan Stevens said. Some suffered scrapes and cuts in the ensuing mayhem that broke out at about 7.15am at the school in Murrysville, about 25 kilometres east of Pittsburgh.
One victim was an adult, authorities said, but none of the names of the victims was being released.
Stevens said the victims were attacked in "numerous classrooms and hallways" of the school.
Watch: 20 hurt in mass stabbing at US high school
Dr Chris Kaufman, the trauma director at Forbes Regional Medical Centre, the closest hospital, said two victims were in surgery and one was awaiting surgery. The three were stabbed in the torso, abdomen, chest or back, which Kaufman called "significant injuries". Seven of those injured were between the ages of 15 and 17.
Twelve of the victims were sent to four hospitals. Hospital officials were still gathering information on their conditions and identities, including the patients' ages.
Speaking outside the school, Morris Hundley said his 14-year-old daughter, Morriah, called him in tears. Hundley came to the school still wearing his slippers, hoping for more information.
"My first thoughts were we need to home school now that this has happened," Hundley said. "Words can't describe how I feel. I'm just thinking of the victims."
Franklin Regional third-year student Anna Davis, 16, said she and a friend were in the hallway when a group of panic-stricken boys "sprinted by".
"I just heard this screaming, and somebody said, 'Somebody has a knife'," she said.
She and her friend ran to the middle school "as fast as we possibly could", where the friend's father met them and took them home.
School director Roberta Cook said the district had done extensive training for a mass casualty at schools. Most of the training done in the district focused on an active shooter, not someone with a knife, she said.
Police said the victims were found in multiple locations because they were following the correct drill to run as far away as possible in the event of an emergency. The school has no metal detectors, but it has a reputation as a relatively safe school.
Yesterday's attack is the latest in a long line of attacks at US school that have inflamed a nationwide debate over gun control in the United States.
But even the December 2012 massacre at Sandy Hook Elementary in Newtown, Connecticut, where 20 young children and six adults were shot dead, ultimately failed to tighten gun-ownership rules.
Thomas Seefeld, chief of police in Murrysville, praised school staff, who worked in close co-ordination with police and who were well versed in emergency procedure.
"It is my opinion that today as unfortunate as it is... that it could have been a lot worse if there was not immediate interaction that occurred," he said.
Associated Press, McClatchy-Tribune, Agence France-Presse