ROCK HILL, S.C. » Police say a 2-year-old South Carolina boy found a gun in the car he was riding in and shot his grandmother in the back.

Authorities were trying to determine today whether to file charges against the woman’s sister, who owns the gun.

Rock Hill police Capt. Mark Bollinger said the 40-year-old woman is expected to survive. She and the child were riding in her sister’s car on Sunday afternoon when the boy found a .357 revolver in the pouch on the back of the front seat and fired the weapon.

Bollinger says the injured woman’s sister owns the revolver.

Investigators are trying to determine whether the child was in a car seat or if any gun laws were violated.

Police didn’t release the names of the child or the women.