"Sam was actually able to tackle the suspect," said Police Chief Thomas Seefeld, according to NBC.
Alex Hribal, a 16-year-old sophomore at Franklin Regional High School in Murrysville, Pa., was charged with four counts of attempted murder and 21 counts of aggravated assault for the stabbing spree.
He will be prosecuted as an adult. Authorities have not yet uncovered a motive.
"[Hribal’s family] offer their condolences," Hibral's attorney, Pat Thomassey, told reporters.
"They're very upset," he said. "They did not foresee this coming. This is a nice, young man. He has never been in trouble. He's not a loner."
Ian Griffith, a senior at the high school, says he saw Hribal stab a security guard then saw King take off after him.
"Mr. King immobilized him," Griffith, 18, told a Pittsburgh TV station.
"He pinned him down and I jumped on top of him as well," Griffith said.
'Love That Man'While others quickly pitched in to help King restrain the suspect, "I think Mr. King was the main hero," he told the station.
Other students agreed.
"Mr. King has always been like a storybook hero, ever since we were little," former student Challon Fisher wrote on Twitter. "Love that man."
Seefeld also praised Nate Scimio, who pulled the fire alarm then later posted a selfie from the hospital. He was stabbed twice.
"The fire alarm being pulled probably assisted with evacuating the school," the chief said, "and that was a good thing that was done."
Students Are Also HeroesOther heroes emerged as well.
Sophomore Brett Hurt stepped in to block Hribal from stabbing his friend Gracey Evans and was stabbed in the back, Evans told the Pittsburgh Post-Gazette.
Brett "has a little sister and he was protecting me like he would protect her," she told the paper.
Gracey, in turn, helped a victim who was stabbed in the torso.
"I said to a few students, we need pressure on this wound, and they gave me some paper towels," she said, "and I held pressure on that wound for 10 minutes."
After medics rushed in and took over his car, she heard Brett "screaming in pain," she says. "I held his hand."
"I held his hand and didn't let go," she told The Huffington Post.
"I kept asking him questions like 'What is your life's dream?' to get him talking," she said. "I got him water. My other friend applied pressure to his back wound because I was talking him through the situation."
Brett was taken to Forbes Regional Hospital, which is where Gracey met the mother of the boy she'd helped, who broke down in tears when she heard what Gracey and others had done.
"All through this I had blood on my hands, blood on my jeans ... I'm still shaking from the experience," she told the Huffington Post.
"I was crying," she says. "I was shaking. I couldn't believe that it happened at Franklin Regional."