They were correct. It may be the same act, but it can violate both a state and federal statute. Generally, they agree on who will take the first prosecution. If it's high profile, McVey, Roof, generally the feds will take the lead, with the state reserving the right to try again, if they don't like the outcome...Probably not, but listening to talking heads talk today, it seems that the DOJ can make a charge of terrorism stick to the driver. Making "hate crimes" or even 1st degree murder stick will be more difficult because the driver did not know any of the victims (one killed, and 11 or so wounded).
One lawyer talking head said pursuing state and federal charges for the same act was not double jeopardy. I will defer to the lawyers on this board.
That said, I hope they throw the book at this a-hole and he never sees a day out of prison again.