Officers responded to a call of shots fired about 7:45 p.m. and entered the store to find four people down, Corona police said.
Two adults with apparent gunshot wounds were taken to a hospital. Police detained the shooter inside the store at 480 N. McKinley St., just off the 91 Freeway, then took him to a hospital after he claimed he was injured.
The man who died has not been identified, police told reporters at the scene.
Lt. Jeff Edwards said the gunman was arguing with someone when he pulled a gun and killed the man.
Corona police said on Twitter that the situation “has been stabilized” and that there is no ongoing threat.
Witnesses told KCAL-TV Channel 9 that gunshots were fired after an altercation inside the store.
They described seeing at least three injured people being taken out of the store, and television footage showed an array of ambulances and law enforcement on scene.
Witnesses said a man with a Mohawk haircut was arguing with a woman with a child inside the store when the shots were fired. One witness said shoppers began stampeding toward exits.
Shoppers described a chaotic scene in the aftermath of the shooting, as they and employees hid in a refrigerated room or stampeded outside.
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 Riverside Press-Enterprise. “An employee came in and helped us out through the emergency exit.”
The Associated Press contributed to this report.
