CORONA, Calif. (AP) — An off-duty police officer opened fire inside a Costco Wholesale warehouse store, killing a man who had attacked him and wounding two others, the Corona Police Department said.

Kenneth French, 32, of Riverside assaulted the Los Angeles Police Department officer Friday night while he was holding his young child, the department said in a statement Saturday. The officer fired his gun, hitting French and two of French's relatives, the department said.

French was killed, the department said. The relatives are in critical conditions at hospitals.

The officer, whose identity is being withheld, was treated and released at a nearby hospital, and the officer's child was not injured, the department said.

The officer was the only person who fired shots in the store, the department said.

The shooting prompted a stampede of frightened shoppers to flee the store east of Los Angeles and seek cover inside.

Witnesses said they saw a man with a Mohawk haircut arguing with someone near a freezer section when shots rang out at least six times. The man involved in the argument was killed, Corona police Lt. Jeff Edwards said.

Witnesses said there was an altercation. Shoppers and employees described terror and chaos when shots rang out shortly before 8 p.m. Friday and police swarmed the store.

Shrieks from inside the store were heard on video recorded by shopper Nikki Tate, who had stopped by with her daughter to pick up steaks and lobsters for Father's Day.

Tate said Saturday she was by the meat section when she heard "about six or seven shots." She dropped to the ground and crawled toward her daughter who was at the other end. They huddled until they were able to escape through a side door.

"I saw people and heard shots and my first thought was 'Jesus, is this another mass shooting?'" she said. "I didn't know if this was a random thing or a domestic thing or if this was a mass shooting. Everything was happening so fast, I just wanted to get me and my kid to safety."

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In the video, her daughter says, "Mommy, we need to go."

The Los Angeles Police Department said in a statement Saturday afternoon that it has launched its own investigation of the incident.

Christina Colis told the Riverside Press-Enterprise that she was in the produce area when she heard six to seven shots and hid with other shoppers in a refrigerated produce room. She said her mother saw people injured on the floor.

"I thought maybe someone dropped a bottle of wine, but then I kept hearing shots," shopper Will Lungo told the Press-Enterprise newspaper. "An employee came in and helped us out through the emergency exit."

Witnesses told KCAL-TV that shoppers and employees rushed to the exits. The station reported that more than 100 people were outside the store at one point. Left behind inside the store were purses, cellphones and backpacks from panicked shoppers, Corona police said.