Costco
Heavily armed police officers exit the Costco following a shooting inside the wholesale warehouse in Corona, Calif., Friday, June 14, 2019. Image Credit: AP

Corona: A gunman opened fire inside a Southern California Costco during an argument Friday night, killing a man, wounding two other people and sparking a stampede of terrified shoppers before he was taken into custody, police said.

Police swarmed the Costco after shots were reported at the huge warehouse store about 80.5 kilometres east of Los Angeles.

Witnesses told KCAL-TV that a man with a Mohawk haircut was arguing with someone near a freezer section when he pulled a gun and fired at least six shots.

The man involved in the argument was killed and two other people were wounded, Corona police Lt. Jeff Edwards said. In a release issued after 1am on Saturday, Corona police said their conditions were unknown.

The suspected gunman said he was injured and was taken to the hospital, Edwards said.

No identities were immediately released. One of those hospitalised was an off-duty officer from another agency. Police said the name of the deceased won't be released until the Riverside County coroner notifies family.

Shoppers and employees described terror and chaos as the shots rang out.

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.

Corona resident Will Lungo, 45, said he and his wife were near the produce and alcohol sections when he heard gunshots.

"I thought maybe someone dropped a bottle, but then I kept hearing shots," Lungo told the Press-Enterprise. "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, at one point, more than 100 people were outside the store.

Corona police say numerous personal items, such as purses, cellphones and backpacks, were left behind by panicked shoppers. The warehouse store is holding shopping bags and other items abandoned by shoppers.