what ultimately appears to be a double murder/suicide. this is all under investigation. the marines included a sergeant and two corporals who are actually training in the officers' candidate school there. and they did locate a handgun which appeared not to be military issue but a personal weapon. the identities of these three marines will not be released until 24 hours after all the families are notified which is the military custom rule if you will. so right now, the investigation is underway and everybody is pretty much guessing exactly how this went down. once they talk to other witnesses who know the three, and gather up the forensics, they'll need to come one a formal conclusion and all that could take weeks. >> nbc's chief correspondent, jim miklaszewski. thanks. i want to bring in dr. zimmer. he is an expert on service members. he wrote the book military