The producer of Insider's 'Boot Camp' series ranks the 6 most intense moments of the show so far

Business Insider's "Boot Camp" series goes inside the training programs of military branches and law enforcement agencies. Senior video correspondent Graham Flanagan counts down the most intense moments he's witnessed while producing the series. Featured training programs include the United States Secret Service, the United States Coast Guard, the United States Marines Corps, the United States Army, and the United States Border Patrol. WARNING: Some images shown in the video may be disturbing.