He meant to kill someone, firing 4 times into a small space (through a door or not) is not a "warning" especially not when you have had time to go get your gun, walk past your bedroom door (Chance of escape) walk down a small corridor, into the bathroom, then stand in front of the Toilet door.
All the "I hope he is innocent" He is not, he either meant to kill Reeva, or meant to kill someone else. He headed toward the supposed danger, not away from it. And I struggle to believe what noise she was making from when she was down a small hallway (lined with cupboards so could assume would muffle some noise anyway), round a corner and behind a locked door. Yet he failed to hear her getting up?. He had been awake for at least 10 minutes, if he had messed around on the balcony, bring in a fan and whatever else he did, them closed the doors (which had been left open despite his apparent extreme fear of intruders), he has not literally just woken up and his eyes need to adjust to the light, yet he goes to the bed, and fetches his gun, and does not see the bed is empty. So fearful of his and her life, knowing the "intruder" is in the bathroom, why not wake her and get her to sneak out the bedroom door then? Or even into the balcony, no he shouts at her, to announce her presence also to this supposed intruder and does not wonder at all why she does not respond.
And if the below is true, it is only surprising that he has not managed to shoot someone before this.
"Interesting that in the documentary, OP's close childhood friend commented that one night he had stayed over at OP's, he had got up in the middle of the night and made some noise. He looked up to see OP coming round the corner gun in hand."