MEXICO CITY (AP) — Employees of a Mexico City movie theater where a 10-year-old boy died from being hit in the head by a bullet fired from outside the building have found 16 spent bullets on the roof on different dates, prosecutors said Wednesday.

A statement said an employee turned in the 16 bullets and told investigators it was common to find spent bullets and bullet holes on the roof around holidays.

The employee told police that on the day the child was shot his manager told him to check the roof, prosecutors said. The statement didn't say what the employee found.

A ballistics expert said Tuesday that the boy was hit by a 9-mm bullet and that a second 9-mm bullet was found on the theater's roof. Authorities were still trying to determine if both bullets were fired by the same weapon.