The BATF had offices in the OKC Federal building. It's interesting that not a single BATF employee showed up for work that day. Also, the BATF had stockpiled a large cache of explosives in the basement of the building. If you look at the photos after the blast, you can see what appears to be low level destruction, which could not have been caused by a truck bomb setting out in the street.
As zero's numbers drop look for another such event to occur. The press is prepping the public for the event with their wild stories of "right wing hate groups."