As for motive: we do not yet know. One thing is certain, a simple suicide does not kill 150 people. When someone kills 150 people they are making a statement. You can call them a terrorist if you wish - but it may be a lone act such as Breivik in Norway or part of a bigger "cause". Depression alone does not cause someone to kill 150 people, nor a desire to die for oneself. I suggest that time will tell in this case.