I've told a few about the details of this dream already but in summary the biggest things that I recall are
1) Confusion. There was confusion about who exactly got shot. At first someone said the President was shot but then it turned out it was a bystander - like a reporter.
2) This happend in a building with a tall entry way (grayish stone) and tall ceiling with a throng of people. There are cars waiting outside maybe waiting for the President to escort him when he is leaving. This happens as he is leaving. Many reporters are around.
3) As time goes by it turns out the assasination attempt was a semi-inside job.