CORONA (CBSLA) – A shooting involving an off-duty Los Angeles Police Department officer was being investigated Saturday after the officer reportedly fired his gun inside of a Costco Wholesale in Corona Friday, killing one person and injuring three.

Officers were sent to the scene at 7:46 p.m. after receiving calls of an active shooter inside, according to the Corona Police Department.

Witnesses said the gunfire started when two men got into an argument inside of the store.

“From my understanding, from some people we talked to, there was apparently an argument inside. Some type of argument that ensued into a gun battle,”  Lt. Jeff Edwards told reporters.

Upon their arrival, officers reported finding one dead and three wounded, including the suspect.

According to CBSLA reporter Joy Benedict, the LAPD had “use of force” investigators at the scene all night as the department conducted their own investigation.

The off-duty LAPD officer reportedly works in the Southwest Division and shot and killed a man during an altercation after feeling threatened.

LAPD released a statement Saturday morning saying, “The Los Angeles Police Department has learned that one of our off-duty patrol officers assigned to Southwest Division was involved in a shooting in Corona Friday night. Our officer suffered minor injuries in the incident and was transported to a local hospital where he was treated and released. The Department has initiated an Administrative Investigation and is working with the Corona Police Department to learn more about the incident.”

The injured were transported to a local hospital and are reported to be in stable condition. Read more at CBS LA