Spoilers - was his (black, 'not' a "racist thing" to mention his color, that's what he is haha, dunno actor's name) FBI agent friend...
... in on it (the terrorist plot to blow up those buildings)?
Is THAT partially why he and those people next to him were reluctant to immediately check the van after he shouted to them that there is a bomb on it and the main reason why he says "We're all authorised to be here, everyone EXCEPT you"?
Cheers.
I kinda thought so, might be wrong though.