In yet another example of the horrific toll gun violence is taking on American children, a 3-year-old girl in Texas shot and fatally wounded her 4-year-old sister Sunday. Harris County Sheriff Ed Gonzalez said the shooting occurred during a gathering involving five family members and friends, when the two children were left alone in a bedroom. After hearing a gunshot, the family burst in to find the 3-year-old holding a semiautomatic pistol and the 4-year-old lying motionless on the ground. “It just seems like another tragic story of another child gaining access to a firearm and hurting someone else,” Gonzalez said, adding that it is “very likely” that an adult will face criminal prosecution for leaving the weapon unsecured. In recent years, gun violence has leapfrogged car accidents to become the leading cause of death among children in the U.S., according to a recent paper by the New England Journal of Medicine.