Updated

A man opened fire in a grocery store Sunday afternoon, shooting and injuring his girlfriend and her sister before police shot him to death, authorities said.

The man arrived at the Rio Ranch Market in Chino, about 40 miles east of Los Angeles, at about 1 p.m. with his two young children in tow, Chino Police Lt. Al Cheatam said.

He shot at four people inside, but hit only his girlfriend and girlfriend's sister. The girlfriend worked in the store's bakery.

"At first everyone thought it was a balloon that went off in the store," Fabio Cebreros, a customer in the store, told KABC-TV. "But then after you heard two more shots just randomly go off, POW! POW! It was chaos."

Police said the man, 25, was holding his girlfriend hostage when they confronted him.

"She had been shot, we could tell that by her bleeding, and he was holding her in a position where he had his gun to her head," Cheatam said. "One of our officers was able to get a good line of sight between him and the hostage and the shooter, and we were able to resolve the situation by the officer firing a round at the suspect."

The girlfriend's sister was airlifted to a hospital in critical condition, authorities said. The girlfriend was treated for non-life-threatening injuries.

It was unclear if the sister also worked at the store.

No names were released.

The two children were in custody of Child Protective Services, authorities said.