The building has three wings and Paddock had a large suite at the end of the wing, the double door to his room was the end of the hallway. So, if he fired through the door those rounds would tend to travel down the hallway.
My question: Forget the maintainence guy. Why was the sucurity guard there? Was he sent first because someone had called frantically about the jambed door? What did the security guard do to prompt Paddock to fire through the door? Did Paddocks room connect (was adjoining) with the room with the jambed door and the security was requesting that Paddock allow the people to pass through?
It seems like Paddock, for whatever reason, saw the security guard as an immediate threat. Otherwise, why not wait it out and the security guard would likely leave. Then he could get on with it as planned. Why shoot someone in the hallway bringing immediate attention to your exact location sooner? Unless there was no choice at that point.
Or...did a guest notice the camera hidden in the food service cart by Paddock and tell the security guard (possibly in person) that there is a pervert on my floor. The security guard then goes to confront Paddock and Paddock panics.
My understanding (perhaps with a little speculation) ...
Both the security guard and the maintenance guy were responding to an electronic door alarm. The alarm was triggered when the door to the stairwell was left open for too long. The door was open because Paddock was monkeying with it to jam it to prevent ingress from law enforcement. Paddock freaked when the security guard showed up. It's not clear whether Paddock was still working on the stairwell door when the security guard arrived (security guard said he heard drilling that I'm wondering may be related to jamming the stairwell door) or if Paddock was in his room drilling his suite door shut when he heard the security guard outside of his room reporting what he found. Either way, Paddock ended up in his room and started shooting through the suite door.
The security guard reportedly found shelter in an "alcove". I'm wondering if that is the area between the double doors of the stairwell. The stairwell door was jammed preventing the security guard from using the stairwell as an escape. Eventually, the security guard noticed the maintenance guy walking down the hall, and shouted a warning. More shots were fired. During a pause, the security guard left his "alcove", ran down the hall, and found another place of safety.