Okay, to throw a curve in the whole "guess the ethnicity of the terrorist" game, here in Canada we recently had a situation where a group of youths, one being from the middle east, but one being a Korean-Canadian and one being a Greek-Canadian, converted to radical Islam and travelled to Algeria where they took part in that gas plant attack back in January.
So, even if the dude's "white", that doesn't preclude the possibility of it being an attack related to radical islamist terrorism.
Of course, it could still be right-wing whackos, or anarchists, or who-the-fuck-knows-right-now.