nearby here. we believe, or at least the investigators tell me they believe that he came to the navy yard today carrying only that shotgun. that once he shot his way in, that he then grabbed two other weapons, taking an ar-15 semiautomatic weapon, perhaps from the guard station there, and then shooting a law enforcement officer and taking the officer's handgun so that by the time he was shot and killed, they recovered three weapons. the shotgun they believe he had in the first place and the other two that he picked up along the way. >> stunning. absolutely stunning. nbc news justice correspondent pete williams. thank you very much. appreciate you being here. >> you bet. all right, more on who the apparent shooter was today. we'll have a live report from one of the places where he reportedly worked before coming to washington, d.c. plus, there's lots more ahead. stay with us. we are confronting yet another mass shooting, and today it happened on a military installation in our nation's capital. it's a shooting that targeted