Emergency crews in Pennsylvania responded Wednesday morning to reports of multiple stabbings at a Westmoreland County high school.
Authorities said that one suspect, a 16-year-old sophomore boy, is in custody following the 7:20 a.m. incident at Franklin Regional High School in Murrysville.
Police said the suspect entered the school wielding two knives before the first class of the day was scheduled to begin. The suspect was subdued by a school police officer and an assistant principal.
"There are a number of heroes…a number of them students," Gov. Tom Corbett said at a press conference in a nearby junior high school.
Nineteen students and one adult were hurt in the attack, Murrysville Chief of Police Thomas Seefeld said in a press conference. Two victims are in critical condition, he said.
"It's a very bad situation," Seefeld said Wednesday evening.
Dr. Chris Kauffman, the trauma director at Forbes Regional Hospital, characterized some of the teenage victims' wounds to the chest, back, and abdomen as life-threatening, according to NBC News. Three of those victims required surgery.
Authorities said that not all of those injured were stabbed by the suspect. Some suffered wounds amid the rush to flee the halls of the building.
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After being taken into custody, the suspect was transported to an area hospital for treatment of injuries to his hands, Seefeld said.
"In all likelihood, he will be charged as an adult," Westmoreland County District Attorney John Peck told reporters.
The weapons were described by Seefeld as approximately 10-inch kitchen knives with straight blades.
Speaking at the evening press conference, Gov. Corbett said the country is beset by mental health problems.
"These incidents clearly reflect mental health issues that need to be engaged and studied," the Republican governor said. "I think we should think about this: What made this young man decide to get up today and do this."
An initial emergency message posted to the school website read:
A critical incident has occurred at the high school. All elementary schools are cancelled, the middle school and high school students are secure. Additional information will be released as soon as possible. Please keep our campus clear of traffic.
Multiple helicopters transported victims to nearby hospitals, WTAE reports.
Parents are instructed to pick up their children at Heritage Elementary school, Murrysville police announced. The high school will be closed over the next several days.
Franklin Regional High School will be closed for several days.
Murrysville is approximately 15 miles from Pittsburgh.