LOS ANGELES, June 16 (Xinhua) -- Police agencies in Los Angeles and the city of Corona are investigating the circumstance of a shooting at a Costco store Friday night by an off-duty Los Angeles Police Department (LAPD) officer, local media reported on Sunday.

A Costco Wholesale store (File photo: VCG)

At 7:46 p.m. Friday night, Corona police officers responded to the shooting at Costco Wholesale located at 480 N. McKinley Street in Corona, 75 km east of downtown Los Angeles, according to a release of the Corona Police Department.

The shooting left one man dead and three others injured.

Investigation has confirmed the off-duty LAPD officer was shopping at Costco with his family before the incident, said the release.

"Without provocation, a male unknown to the officer's family assaulted the officer while the officer was holding his young child. This attack resulted in the officer firing his weapon, striking the male and two of the male's family members," said the release.

The male was shot dead by the officer. His two family members are being treated at local hospitals and are in critical condition, according to police.

The off-duty officer was transported to a local hospital, where he was treated and released. His child was not injured during this incident, said the release.

The Riverside County Coroners Office has identified the deceased male as 32 year-old Kenneth French from Riverside.

The officer's gun was the only weapon involved in the incident, contrary to earlier reports, according to authorities.

"The investigation has revealed this was an isolated occurrence within the store and was not an uncontained active shooter incident as the preliminary information had been communicated to initial officers," said the release.

The Corona Police Department is working closely with the Riverside County District Attorney's Office who will be evaluating the facts and circumstances of this incident, said the release.