Once outside, the homeowner, whose name was not released, said he was hit over the head with a baseball bat.
The three struggled on the ground, grappling over control of the rifle. That's when the homeowner fired off three to five rounds. Both alleged trespassers were hit.
Kenneth Hergenreder, 41, and Fred Hergenreder, 43, were later found nearby and taken to an area hospital. Deputies recovered a baseball bat, rifle and knife from the men.
No arrests were made and the incident remained under investigation.
Mead Valley is an unincorporated area of south of Riverside.
City News Service contributed to this report.