Update: One dead and three injured in Southern California Costco shooting

CORONA, Calif. (AP) -- A gunman opened fire inside a Southern California Costco during an argument Friday night, killing a man, 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 store about 50 miles southeast of downtown Los Angeles.

Witnesses told television news stations that the gunman was arguing with another man near a freezer section when he pulled a gun and fired at least six shots.

The gunman killed one person, wounded two others, and was injured himself, authorities said.

One of the injured was an off-duty officer from another law enforcement agency. 

Authorities on Saturday announced that the injured officer was an off-duty Los Angeles police officer, who was treated at the hospital for minor injuries and later released.

Police said the identity of the person killed will not be released until the Riverside County coroner notifies the family.

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

Christina Colis told reporters 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.

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

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

At one point, more than 100 people were outside the store.