(CNN) -- A day after a Pennsylvania student rampaged through his high school's hallways, stabbing wildly with two kitchen knives, hints of a motive remain elusive.
Who is 16-year-old Alex Hribal, and what troubled him?
Hribal was charged as an adult and faces four counts of attempted homicide and 21 counts of aggravated assault related to the 21 people he wounded.
Some classmates at Franklin Regional Senior High School describe him as having few friends and being quiet, but also as a "really nice kid."
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