Evocations requires line of sight

I ran one of my hands back over my hair. “There’s only two ways anyone could have managed this. The first is by evocation. Evocation is the most direct, spectacular, and noisy form of expressed magic, or sorcery. Explosions, fire, that sort of thing. But I doubt it was an evocator who did this.”
“Why?” Murphy demanded. I heard her pencil scritching on the notepad she always kept with her.
“Because you have to be able to see or touch where you want your effect to go,” I told her. “Line of sight only. The man or woman would have had to be there in the room with them. Tough to hide forensic evidence with something like that, and anyone who was skilled enough to pull off a spell like that would have had the sense to use a gun instead. It’s easier.”

Storm Front Chapter 2, Page 17