Sure there can be lots of "what ifs".  But according to the latest time line (subject to change) he shot 200 rounds inside before he ever unleashed on the crowd.  I've been to a lot of hotel rooms and I would think I would hear shots being fired if I were in the same hallway, or above or below him. And there are service people everywhere.  There is so much to this story that doesn't make sense.  I still wonder why he stopped shooting after 10 minutes with all that ammo still in the room and the fact that police hadn't responded nor had confronted him yet.  And the fact that he appeared to have an escape plan.