Not in this particular case though. Here we deal with a kid who, it seems, is perfectly verbal, throws the threats of very hardcore violence left and right, smuggled the gun into school and then, unprovoked at the moment, pulled that gun out, aimed at the teacher and shot her. That's not your usual case of a disabled kid who has problems with the sensory input, communication or both and has a hard time with controlling and processing their emotions.
Here we deal with something else that requires very thorough investigation. The propensity for using violence as a solution, a planned violence, does not appear from the thin air. This kid learned it from someone. Who ? How does his family environment look like? What did the parents do to deal with quite obvious antisocial tendencies of their child? What kind of therapy the child got for the issues connected to his disability ? What kind of media had he access to? Was he using them under supervision ?
It's a complicated matter and there is a lot of questions that have to be answered.