They should not panic or criticize the child. Instead, they should respect the privacy of the child, and assure the child that they are not at fault. The most important next step for the employee is to report it to the director of the park district or designated authority person of the park district. The park director should report it to the proper authority. No non-qualified park employee should do any investigation.
Suspicion is enough for reporting.
Professionally trained persons need not control the reporting to prevent innocent people being accused of destroying statements. Directors should contact the local police department for their procedures involving child abuse. Many park districts are unaware they are legally required to report child abuse under state law.