(CNN) -- It would seem no one saw it coming -- not his parents, not students at his school.
Described by his lawyer as "a typical young kid" who has "never been in trouble," 16-year-old Alex Hribal shocked the people in his life and the nation Wednesday when he allegedly went on a rampage at his high school in Murrysville, Pennsylvania, stabbing or slashing 20 students and a security officer.
No one knows yet what might have motivated the attack.
But pieces of Hribal's story are starting to come together, so far painting a portrait of a teenage boy no one ever expected to show such violence.
"He's a typical young kid. He's a B+ student. The family is like Ozzie and Harriet. They have dinner together every night," said his attorney, Patrick Thomassey.
"All the students liked him. He wasn't a loner. He worked well in groups, and this happened. So there's a reason for it -- that's what I'm saying. And we have to get to the bottom of that," the attorney said.
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.
His attorney said he would file a motion to move the case to juvenile court. He also said it would be important to have his client examined by a psychiatrist to help determine "where he is mentally."
"I'm not sure he knows what he did, quite frankly," Thomassey said, adding that Hribal feels remorse.
"He's scared. He's a young kid. He's 16, looks like he's 12. I mean, he's a very young kid, and he's never been in trouble, so this is all new to him," the attorney said.
'Shy kid ... kept to himself'
Mia Meixner, a student at Franklin Regional Senior High School, witnessed a part of Wednesday's attack.
"He (Hribal) was very quiet. He just was kind of doing it," she said. "And he had this, like, look on his face that he was just crazy and he was just running around just stabbing whoever was in his way."
She said she didn't know the boy well, but he had been in a lot of her classes.
"From past experiences with him, he hasn't been violent at all. He's actually been a really nice kid from all the times I've talked to him. He was just more of a shy kid, and kept to himself," she said. "He was nice whenever you would talk to him. I never thought anything bad would happen with him."
Meixner said she didn't know of Hribal getting bullied, which was something his attorney also said.
"I'm not gonna comment on what my client had to say, but I don't know anything about any bullying," Thomassey told reporters.
Earlier, FBI agents seized Hribal's personal computer in hopes of discovering a possible motive, according to spokeswoman Kelly Kochamba.
'Not a troubled young man'
Hribal appeared in court shortly after the attack, where it was revealed he has lived in Murrysville since he was 2. He has an older brother.
Westmoreland County District Attorney John Peck argued against bail, saying there could be no conditions that would protect the community and noting Hribal made "statements when subdued by officials that he wanted to die."
A judge agreed, and Hribal is being held without bail at the Westmoreland County Regional Youth Services Center.
He did not speak to reporters as he was led into a waiting police car.
According to Dan Stevens, the county deputy emergency management coordinator, Hribal had a very minor Facebook presence and didn't have much experience on Twitter. He is not believed to have had a cell phone.
Adding to the mystery, Thomassey said his client "was not a troubled young man to this point."
"They (his parents) offer their condolences to everybody involved in this case. They're very upset. They did not foresee this coming at all," the attorney said. "This is a nice young man. He's never been in trouble."
CNN's Chelsea J. Carter, Paul Courson and Pamela Brown contributed to this report.