Re-reading this, because security was pushing the wizard constantly, the wizard, in an attempt to fight or flight (his scroll was taken away), decided to push back. Shot a fireball. Broke a viral container. The black plague spread, people died. It was not like it was unprovoked, however. Crap happens, it gets out of your grasps and goes out of your control, people die as a result. But there was build up of conflict with a backstabbing officer.
That's what I see which happened.