As a nurse who has worked in mental health, I am strongly against the media trying to further stigmatize people, who suffer from mental health issues, by attaching them to these perfectly logical acts of violence.
To premeditate mass shootings type of attacks, you have to think clearly about it. The attacker searches for a weapon of choice, learns to use the weapon of choice, keeps a back weapon, scouts the future scene of the crime, and most importantly, he has enough will power and patience to wait for the perfect opportunity to strike.
This is military style thinking. Are our soldiers "crazy"? In my experience, people with mental health issues will commit suicide before homicide. They often get violent towards others, only when others get in their space. It is rarely premeditated, and most often a reaction towards typically a single individual.
The idea that a human has to be "crazy" to kill a bunch of people is just ridiculous. American soldiers go overseas and kill a bunch of people, who have never directly done anything wrong to them. The motives may be different, but the execution is the same.