MURRYSVILLE, Pa. - When a knife-wielding, black-clad sophomore stormed out of a classroom in the science wing of Franklin Regional High School on Wednesday, instincts kicked in.

In sophomore Brett Hurt's case, according to his friend Gracey Evans, the instinct was to protect.

Brett "has a little sister, and he was protecting me like he would protect her," said Evans, a junior.

Hurt blocked the knife-wielder, whom authorities later identified as Alex Hribal, from reaching Evans, she said.

For that, Hurt took a knife in the back. According to the Evans family, he was doing well but was expected to remain overnight at a hospital.

When tragedy strikes, and notably when the victims are young people, heroes are an important part of the healing process, said Anthony P. Mannarino, vice chair of the department of psychiatry at Allegheny General Hospital and director of the Center for Traumatic Stress in Children in Adolescents.

"These events are horrific," Mannarino said. "For others to know that their colleagues or their classmates did the right thing or did an important thing to protect others is always uplifting in these terrible situations."

"Today, our staff members acted quickly and saved the lives of many students," Superintendent Gennaro Piraino said, adding the students themselves did the same.

Hope Demont said sophomore Nate Scimio jumped in front of three students who were being attacked. "There were seniors running everywhere trying to see if they could carry someone, help someone," she said.

Mark Drear, vice president of Capital Asset Protection, which provides security guards for the school, said one student pulled the fire alarm, trying to spur an evacuation.

As the assailant continued down the suddenly crowded 200-foot-long science wing of the high school, he encountered two security guards and two vice principals.

Ian Griffith, an 18-year-old senior, said he saw assistant principal Sam King talking to the attacker, who then stabbed a security guard.

King jumped on the student and Griffith said he then jumped on top of the pair. Griffith said he tried to hold down the attacker's hands and arms until King told him to go find an ambulance.

"I think that Mr. King is the real hero," Griffith said.

Meanwhile, as the injured Brett Hurt lay on his stomach, Gracey Evans held a victim who had been stabbed in the torso.

"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," Evans said.

Less than a minute later, medics rushed in and took over.

"I hear my best friend start screaming in pain," Evans said of Hurt. "I held his hand."