A teenage boy wielding two kitchen knives went on a stabbing rampage at his high school in Murrysville, Pennsylvania, early Wednesday, before being tackled by an assistant principal, authorities said. 

Twenty students and a security officer at Franklin Regional Senior High School were either stabbed or slashed in the attack, Westmoreland County District Attorney John Peck told reporters. 

The accused attacker was been identified as 16-year-old Alex Hribal, according to a criminal complaint made public. Hribal, who was arraigned as an adult, faces four counts of attempted homicide, 21 counts of aggravated assault and one count of possession of a weapon on school grounds, the documents show. 

"I'm not sure he knows what he did, quite frankly," Hribal's attorney, Patrick Thomassey, said, adding he would file a motion to move the case to juvenile court. 

"...We have to make sure that he understands the nature of the charges and what's going on here. It's important that he be examined by a psychiatrist and determined where he is mentally." 

A doctor who treated six of the victims, primarily teens, said at first they did not know they had been stabbed. 

"They just felt pain and noticed they were bleeding," Dr. Timothy VanFleet, chief of emergency medicine at the University of Pittsburgh Medical Center, told CNN. 

"Almost all of them said they didn't see anyone coming at them. It apparently was a crowded hallway and they were going about their business, and then just felt pain and started bleeding." 

Arguing against bail for Hribal, the district attorney told the court that four of the victims were in critical condition, including one who was "eviscerated." There's a question whether the victim will survive, Peck said. 
What else did his lawyer have to say?
"I'm not sure he knows what he did, quite frankly," Hribal's attorney, 