Murrysville, Pennsylvania (CNN) -- A day after a Murrysville, Pennsylvania, teen allegedly rampaged through his high school's hallways, stabbing wildly with two kitchen knives, the first hints of a possible motive began to emerge.
The attorney for 16-year-old Alex Hribal raised the specter that his client may have been bullied, telling CNN affiliate WTAE in Pittsburgh on Thursday that it looks like some kind of "bullying event" may have played a role.
"I think a lot of things have happened. I don't want to comment specifically, but I think there are some things that occurred that led to where we are today," Patrick Thomassey said.
But an FBI official, familiar with the investigation, discounted bullying as a motive.
"He was disaffected but not bullied," the official said on condition of anonymity.
Hribal, a sophomore, was charged as an adult and faces four counts of attempted homicide and 21 counts of aggravated assault in connection with Wednesday's attack at Franklin Regional Senior High School that left 20 teens and one adult wounded.
Some classmates at the school describe Hribal as having few friends and being quiet but also as a "really nice kid," a description that contradicts the image of a knife-wielding teen offered by authorities.
Murrysville Police Chief Tom Seefeld said investigators haven't yet made sense of the mass stabbing.
"We believe, through the investigation, that this was random," he told CNN's "New Day." "We don't have anybody that was targeted, as far as we know at this point."
Still, there were more questions than answers about what led the teen to allegedly attack his classmates with two steak knives believed to have been taken from his family's home.
"We're going to try to figure out what happened here. Obviously, there's a problem. You just don't leave and go to school, and do what he did yesterday," Thomassey told CNN earlier in the day.
There is "some deep-rooted problem somewhere that caused him to do this."
One thread that police are looking into is the possibility that there was a phone threat the night before, Seefeld said.
But no immediate evidence has been found to confirm such a call, and Thomassey discounted the allegation.
"He was home all night the night before this occurred, with his parents," he told WTAE. "They did not see him on the phone arguing with anybody."
The FBI has seized electronics belonging to Hribal, including a computer and cell phone, and will analyze them for any clues, the police chief said.
In a telephone call Thursday, President Barack Obama assured Franklin Principal Ron Suvak that the FBI will continue to assist in the investigation, the White House said.
'All kind of a blur'
Questions are also being raised by residents of Murrysville, a quiet middle-class enclave with a population of 20,000 east of Pittsburgh.
How did this happen, and why?
"We are so small compared to other communities," said Paula Fisher, who left Pittsburgh to move to Murrysville almost 20 years ago.
"I came out here purposely to raise my children in a school district that we felt was safe as well as academically sound."
The mother of one of the teens wounded in the attack said everyone must ask themselves what alienated the suspect so much that he allegedly stabbed and slashed nearly two dozen people.
"...We need to look and say, how are our children coping with social skills these days? How are they with other children? How are they being tested in the world for negative or positive ways?" said Amanda Hurt.
Her son, Brett, was in the school hallway when he saw a "kid" run by and hit him in the back.
A friend who was with him started screaming.
"I didn't really know what was going on at the time," Hurt told reporters. "It was all kind of a blur."
As the attacker continued to charge down the crowded hallway, Hurt began to wonder if he was going to survive or die.
Speaking from the hospital, Hurt said he suffered a stab wound in the back and a bruised lung. He expected to be released as early as Thursday.
He reflected on whether Hribal would have chosen the path he allegedly did if he had had more friends or a better support group.
"I feel he has some issues he has to work out," Hurt said.
Another student at the school who witnessed the attack said the attacker didn't utter a word.
"He was very quiet. He just was kind of doing it," Mia Meixner 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."
The attack ended when the assistant principal, Sam King, tackled the teen, authorities said.
The accused attacker, Hribal, lived on the same street as King, just two houses down.
'Not a dysfunctional family'
Hribal couldn't seem more normal, the way his lawyer describes him.
"This is not a dysfunctional family," Thomassey, told CNN on Thursday. "They're like the Brady Bunch. These parents are active with their two sons, and we're trying to figure out what happened."
The young man also did not seem to embody the cliche of digitally connected youth.
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.
Thomassey said he would file a motion to move the case to juvenile court.
Westmoreland County District Attorney John Peck has argued against bail, saying that there could be no conditions that would protect the community and that Hribal made "statements when subdued by officials that he wanted to die."
Hribal is being held without bail at the Westmoreland County juvenile detention center. He was treated for injuries to his hands, police said.
The students who were hurt range in age from 14 to 17, emergency coordinator Stevens said. The injuries were stabbing-related, such as lacerations or punctures.
CNN's Pamela Brown and Mary Kay Mallonee reported from Murrysville, and Chelsea J. Carter reported and wrote the story in Atlanta. CNN's Ben Brumfield, Mariano Castillo, Miguel Marquez, Chris Cuomo, Stephanie Gallman, Paul Courson and Shimon Prokupecz contributed to this report.