MEXICO CITY - The slaying of a 10-year-old boy at a movie theater to see the animated Disney film "Wreck-It Ralph" has caused a commotion in Mexico's capital and cast a harsh light on the inaction of police and prosecutors.

Someone fired a single gunshot that struck the head of Hendrik Cuacuas while his father and 12-year-old sister sat beside him. The slaying occurred Nov. 2, but news of it only broke this week.

Public anger prompted investigators to seal off the cinema and continue interrogating employees Tuesday about the youngster's slaying.

Cinepolis, the world's fourth-largest theater chain, also came under criticism for allowing the feature film to continue after the mortally wounded boy's evacuation.

The father of the boy, Enrique Cuacuas Miranda, an engineer, said he took his son and daughter to see "Wreck-it Ralph" at a multiplex theater in the Ixtapalapa area of the capital. About half an hour after the feature began, Cuacuas said he "heard something whistle by my ear." Moments later, he turned to see his son in convulsions.

Unbeknown to Cuacuas, someone in a row in front of his family had fired a gun at his son's head. For an unknown reason, the shot produced neither a loud sound nor a muzzle flash.

Employees stopped the film and turned on the lights. A gurney arrived but it was not immediately clear that the boy had been shot, only that he was in convulsions and bleeding from the head. He died two days later.

More than a week after the incident, the city prosecutors office promised to take action.