Alex Hribal, 20, is taken back to prison Monday after he was sentenced for attempting to kill 21 people at Franklin Regional High School in 2014. He was sentenced to 23½ to 60 years in prison and was ordered to pay more than $269,000 in restitution.

GREENSBURG — A man who pleaded guilty to stabbing 20 fellow students and a security guard at his suburban Pittsburgh high school was sentenced Monday to 23½ to 60 years in prison.

A judge also ordered Alex Hribal, 20, to pay more than $269,000 in restitution and rejected defense contentions that his actions stemmed from bullying.

Hribal pleaded guilty in October to a weapons charge and numerous attempted homicide and aggravated assault charges. He was 16 when he used two eight-inch kitchen knives to stab and slash his way through the hallways of Franklin Regional High School in Murrysville before classes began on April 9, 2014.

Four students were critically injured at the school near Pittsburgh, including one who required a liver transplant. All survived and have since recovered.

Hribal said in a brief statement that he had been bullied by fellow students and regretted trying to deal with his mental health issues himself rather than seeking help.

“My biggest mistake was falsely believing that if I took revenge ... I would be happy,” he said, calling for an end to bullying and urging people with mental illness to seek treatment. “I want people to not make the same mistakes I did.”

Westmoreland County Judge Christopher Feliciani, however, said “although some have alluded to your actions as being caused by bullying, the facts do not support that.” He said his sentence was based on the seriousness of his actions and the physical and emotional scars left on the victims and their families.

Psychiatrists for both the defense and prosecution testified earlier that Hribal purposely carried out the attack on the birthday of Columbine High School killer Eric Harris, whom Hribal “worshipped,” and hoped to do so on the 15th anniversary of the 1999 Columbine massacre but couldn’t because the school wasn’t in session that day.

Defense attorney Patrick Thomassey unsuccessfully sought to transfer the case to juvenile court or to have his client allowed to plead guilty but mentally ill to the charges.

“He should be going to a mental hospital,” Thomassey said. “That’s what he needs. I’d take him home with me now.”

Kolden Cook, 19, a sophomore at the time who was stabbed in the back, also addressed the court.

“Does he feel a sense of righteousness or a sense of regret?” he asked. “If he feels the latter, there might be some hope.”