Answer:
What I believed happened
Explanation:
Let's understand the people who were near: there were two people who had walked past this house and heard a woman scream, followed by a gunshot. Now, that already probably has two things, either she was robbed and shot, or stabbed herself or was murdered. But, we then see a man bleeding on the ground, so there's two things that I believe that could've happened:
1. The woman found the man being shot in that given moment by somebody random, or somebody who had broken into the house. She probably wasn't in the sight or view that she could've been killed so she probably kept hidden and screamed, and the man went out into the yard probably trying to escape the intruder as he was bleeding out from the encounter.
2. A man stumbled out bleeding, maybe he had made his way out after probably getting shot accidentally or by something that had happened, but he was too close to the door and maybe was trying to call for help. As for the woman, she was probably scared by that given moment, maybe didn't even know it had happened in that exact time.
But there is one thing that I believe could've been the exact scenario:
The woman was screaming right before the gunshot, I still believe somebody could've entered, but she could've shot the man (depends on the scream that was let out) or maybe somebody else was about to shoot the man or it was an accident or a purposeful action. The man was surprised by it, because as he ran out and laid down on the floor that can show that he was really scared and surprised by it, if he was expected or known of it, the guy would've reacted differently, but in this instance it was a shock for him.
(This the best I could probably get out of this, I hope that this is good for you)