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

A judge on Monday also ordered 20-year-old Alex Hribal to pay more than $269,000 in restitution.

Hribal pleaded guilty in October to a weapons charge and numerous attempted homicide and aggravated assault charges.

Hribal 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.