A teenager with two butcher knives attacked fellow students at a suburban high school outside of Pittsburgh, Pennsylvania in America’s northeast.  Twenty people – all students except for one security guard – are recovering from various wounds and three are in critical condition.

It happened early in the morning before classes at Franklin Regional Senior High School in Murrysville, the black clad 16-year old suspect chased his victims from room to room, some of them seriously wounded and bleeding.  Most of the targets were boys, and doctors said the wounds were several centimeters deep.  Kids were stabbed in the stomach, back, and arms.  One 17-year old girl had emergency reconstructive surgery for slashes to her face. 

The security guard was stabbed as he and the vice principal took the kid down.  Police as of Wednesday afternoon, local time, had no idea of the motive.

One student told reporters that the 16-year old suspect was "sort of a shy person," who "never seemed like someone who would do anything violent.  He never seems very upset or anything of that."  The same student said that he never witnessed the suspect being bullied in the past, however he assumed that it was going on.

But an alumnus painted a darker picture.

"It was pretty common knowledge between all the kids that he had made some death threats," said the young man who graduated from the school in 2010 and whose sister is a sophomore there.

"I guess the kids who got the threats just assumed it’s no big deal," he said.