Department policy states that when an internal investigation is conducted, the subject is placed on administrative leave with pay, a Huntington Park police spokesman said.
Lt. Neal Mongan, Huntington Park's police administrative representative, said the officer is back on duty following the investigation of what transpired Oct 4.
Criminal charges related to the shooting have yet to be filed against anyone involved in the incident.
The case is still pending review, said Christopher Lee, spokesman for the San Bernardino County District Attorney's Office.
Authorities said the shooting was sparked by road rage but did not say who detectives believe was the aggressor or provide details of the incident.
Eugene Lee, Brian Sloma and Addison Weeks were all arrested after a San Bernardino County sheriff's investigation.
Sloma and Weeks were shot and wounded that October night.
According to sheriff's officials, the incident began on the 71 Freeway. Both drivers pulled off the freeway and stopped at The Shoppes.
The off-duty officer told investigators that four men got out of their vehicle and approached him. The officer said he saw objects in the hands of two of the four men.
The officer then opened fire, wounding Weeks and Sloma.
Weeks was taken to Arrowhead Regional Medical Center in Colton with multiple gunshot wounds. Sloma was treated at the scene before being sent to the hospital.
"Regarding the criminal case I have to refer you to the DA's Office," Mongan said. "I have no further comments."
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