one of in the victims shoulder to shoulder with navy commander. tim jurvis. >> i saw him drop in front of me. he was shot in the head. >> reporter: finally at 12:14, police announced they fatally shot the gunman identified by the fbi as aaron alexis, a former navy man who most recently worked for the navy as an i.t. civilian contractor. the navy yard staying on lockdown more than six hours. survivors told to hide in place. some barricading themselves in top-secret secure closets. others under their desks. navy captain mark vandroff was one of those evacuated from his office. >> we heard gunfire, and we looked up, and there were two bullet holes in the top of the conference room. >> reporter: police are starting to understand the how of what happened here but not the why. no clues to the motive. only saying that so far no indication of terrorism. jim avila, abc news, washington. our coverage continues from the scene near the navy yard with abc's karen travers.