there, witnesses say they were concerned a little bit about the back doors of the building, whether or not that offered a path in, but fundamentally this is the question, how does somebody with all that going for them wipnd up in a building wit a gun. >> how did that happen? there's this huge question of how in the world did he get in with these three guns? >> once he got in things happened very quickly. at about 8:18 the first gunfire happened and people were told to shelter in place. by 8:21, authorities were already engaging him inside the building, by 8:25 other police had arrived from the city and they were in a running battle with him. nonetheless, he managed at some point to be shooting from up on the fourth floor down through an atrium at some of the people