I only discounted some of the races because of the low probability for organized terrorism in a group fashion might be hard to imagine, such as White or Black or Native American. The only exception might be if a White Chechniyan were involved, or a black Portland cell type were involved. I think all the indications are away from Hispanic, White and Black, and certainly Northeast Asia (China, Japan, Korea,), and perhaps more in South Asia and Middle East.
I am, of course, racial profiling here, but I would be a hypocrite to support the tactic and not indulge in a little of it meself here on FR!