MURRYSVILLE, Pennsylvania - A 16-year-old student wielding two knives went on a stabbing rampage in the hallways of a Pittsburgh-area high school on Wednesday, wounding 22 people before he was tackled by an assistant principal, officials said.
The attacker moved furtively through Franklin Regional High School halls, stabbing his victims in the torso and slashing their arms and faces, students and officials said. Some of the injured taken to nearby hospitals were in critical condition, doctors said.
Students described a scene of panic, with the school hastily evacuated after a fire alarm was pulled. The unidentified sophomore suspected in the attack was in police custody, said Tom Seefeld, chief of police in Murrysville, Pennsylvania.
"He did it so stealthily that at first no one knew what was happening," said freshman Josh Frank. "We heard a girl scream bloody murder. Then two seniors were running down the hall and we followed them out of the school."
The attacker, described by a classmate as a quiet person who kept to himself, started his rampage at around 7:13 a.m. (11:13 GMT), walking along the hallways to several classrooms at the school in Murrysville, 20 miles (32 km) east of Pittsburgh, officials said.
Assistant Principal Sam King tackled the boy, who was armed with two "straight knives" of about 8 to 10 inches (20-25 cm), and an armed security officer handcuffed him with help from King, Seefeld said.
Westmoreland County District Attorney John Peck told a news conference that the teen would likely be charged as an adult, possibly with aggravated assault and attempted murder, and then his name would then be released.
Twenty-one students and a security officer were stabbed in the incident, said Dan Stevens, a spokesman for Westmoreland County emergency management.
Two other students suffered nonstabbing injuries - "things like scraped knees and twisted ankles," trying to get out of the school, Stevens added. He added the teenage suspect was not counted among the wounded.
Among those praised for heroics during the incident was Nate Scimio, the student who pulled the fire alarm and helped shield classmates, witnesses said.
"There's not enough words to describe how much of a hero he is," classmate Trinity McCool posted on Facebook.
The victims, most of them 14 to 17 years old, were transported to area hospitals, four by medical helicopters. Several had life-threatening injuries, hospital officials said.