It has been a long time since I read the accounts of what happened but the above is entirely wrong IIRC. Randy Weaver was not with his son, Samuel, and Harris who were out hunting. One FBI agent was hidden in the underbrush wearing a ghillie suit. The dog, which belonged to Samuel, started barking at the hidden agent. The agent, fearing exposure, shot the dog.
Samuel shot in the direction the shots had come from not knowing who had shot his dog or whether he and Harris were under fire also. He shot the agent. Samuel was wounded by return fire from the agent. Harris and Samuel ran back to the cabin. I don't recall if Harris carried him back but he was carrying him when he got to the property and put him in a shed near the house. Samuel may have been dead at that point.
That is what has brought all this bubbling back to the surface, apparently in a fairly big way.
Best regards,
As I recall you post is basically correct except that they were Us marshals, not FBI. The FBI was called in after the Marshall was killed.