A 16-year-old Texas girl faces a charge of aggravated assault with a deadly weapon in what investigators say was the accidental shooting death of her 12-year-old sister.

Galveston police say the teenager was playing with a gun Sunday morning at home when it accidentally went off, striking her sister in her upper torso. The younger girl died at a hospital.

Police Lt. D.J. Alvarez said Monday their mother also may face charges for making a firearm accessible to a child. Alvarez says the mother was home when the shot was fired.

The 16-year-old is in juvenile custody in Galveston.