 At least two witnesses have come forward and told the media they warned police officers about a gunman crawling on the roof. One rally goer told CBS News, I was just standing there like everyone else, just waiting for Trump. And as Trump started, I noticed two officers looking for somebody. So I was looking around myself and seeing a guy, like your English, seeing a guy on top of one of the buildings go in between one building to the next and went and told the officer he was up there.